Read the most frequently asked 100 top Immunology multiple choice questions and answers PDF for freshers and experienced. Immunology objective questions and answers pdf download free..
Immunology Multiple Choice Questions and Answers PDF Experienced Freshers
1. Give the classification of hypersensitivity?
Hypersensitivity is classified into five types-
? 1. Anaphylaxis
? 2. Antibody dependant cytotoxicity
? 3. Immune complex mediated diseases
? 4. Delayed type ‘o’ cell mediated hypersensitivity
? 5. Stimulatory hypersensitivity
2. What is anaphylaxis?
It is most rapid hypersensitive reaction. It responds within minutes of applying a stimulus and can get localize. Reactions are mediated by release of pharmacologically active substances.
3. What is hypersensitivity?
The inflammatory response produced by inflammatory molecules result in tissue damage and some times even death. We call this as hypersensitivity or allergy.
4. What is delayed hypersensitivity?
We can recognize the Symptoms only days after exposure. This is delayed hypersensitivity (DTH).
5. What is a myeloma protein?
It is a monoclonal immunoglobulin produced from a myeloma cell.
6. What is opsonin?
Opsonin is a substance, which promotes phagocytosis of antigens by binding to them.
7. What is an incomplete antibody?
Antibody can bind to an antigen but cannot induce agglutination is called incomplete antibody.
8. What are iccosomes?
The particles coated with immune complexes and are released from follicular dendritic cell extensions, are called as iccosomes.
9. Name the scientists who classified hypersensitivity.
Coombs and Gell
10. What are hypersensitive reactions?
If humoral or cellular immunity is switch on to high for length of time, tissue damage may occur. Such reactions are called hypersensitive reactions.
11. What is auto immunity?
Disease caused by immunological reaction to self-antigen. Such type of diseases is classified either organ specific or non-organ specific.
12. Name some of the immuno suppressive agents.
? Cytotoxic agents such as chlorambucil, cyclophosphamide, and azathioprine
? Glucocorticoids
? Cyclosporine
? Antilymphocyte antibodies
13. What is immuno suppression?
Immuno suppression is particularly given to the patients who are undergoing organ transplantation in the treatment of autoimmunity, graft rejection and in allergy conditions.
14. What are the types in adjuvants?
? 1. Organic adjuvants
? 2. Synthetic adjuvants
? 3. Tuftsin
15. What is an adjuvant?
Adjuvant potentates the immune response Vaccines need to be enhanced by some substances, these substances are called adjuvants.
16. What is vaccination?
Vaccination means exploiting the immune system to protect against infectious diseases. Vaccination is done to protect against lethal diseases such as mumps, rubella, poliomyelitis, diphtheria, tetanus, small pox etc.
17. What is attenuation?
Natural behavior of an organism without causing disease is called attenuation i.e. reducing pathogenesity of the organism.
18. What is secondary immune response?
Secondary immune response occurs when second exposure to the same antigen occurs after weeks, months or after years.
19. What is inductive or latent period?
After immunogen is introduced no antibody is detected, this is latent or inductive period. In this period, immunogen is recognized as a foreign substance.
20. What is primary immune response?
First exposure to an antigen produces primary immune response.
21. What is a binder?
The binding protein (usually antibody) which binds to the ligand is called as binder.
22. What is an analyte or ligand?
The substance whose concentration is to be determined is called as an analyte or ligand.
23. What is importance of radio immuno assay?
It is the most sensitive technique used for detecting antigen or antibody. This type of reaction is also called as binder ligand assay.
24. In radio immuno assay what is the used to label an antigen?
In this technique, the antigen is generally labeled with a- emitting isotopes such as I125.
25. What is radio immuno assay?
It is a competitive binding assay in which fixed amount of antibody and radiolabelled antigen react in the presence of unlabelled antigen.
26. What is western blotting?
Identification of specific protein in a complex mixture of proteins can be accomplished bye a technique that is known as western blotting.
27. What are the enzymes used for labeling of antibodies?
Enzymes used for labeling of antibodies are horseradish peroxidase, alkaline phosphatase, ß- galactosidase, lacto preoxidase, etc.
28. What is the significance of indirect ELISA?
It is used for the detection of the presence of serum antibodies against immuno deficiency virus (HIV, the causative agent of AIDS).
29. In how many ways ELISA can be carried out.
It can be carried out in three ways.
Indirect ELISA
Sand witch ELISA
Competitive ELISA
30. What is the significance of ELISA?
It is used for the detection and for identification of either antigen or antibody.
31. Name two enzymes that have been employed for ELISA.
1. Alkaline, phosphatase, horseradish, preoxidase
2. Para nitro phenyl phosphatase
32. What is the basic principle of ELISA?
The basic principle is an enzyme conjugated to n antibody reacts with a colorless substrate to generate a colored product.
33. What is the full form of ELISA?
Enzyme Linked Immuno Sorbant Assay.
34. What are the uses of indirect immuno fluorescence?
1. For identifying bacterial species
2. Detecting antigen-antibody complexes in autoimmune diseases
3. Detecting compliment components in tissues.
4. Localizing hormones
35. What are the advantages of indirect immuno fluorescence?
The primary does not need to be conjugated with label.
It increases the sensitivity of staining because multiple fluorochrome reagents will bind to each antibody molecule.
This method has great flexibility.
36. What is indirect immuno fluorescence?
In a method the primary unlabelled antibody is detected with a number of reagents have been developed for indirect staining. The most common is fluorescence labeled anti isotype antibody such as fluoroscin labeled goat- mouse antibody.
37. What is the disadvantage of direct immuno fluorescence?
A separate fluorescent conjugate have to be prepared against each antigen to be tested.
38. What is direct immuno fluorescence?
In this method, the species antibodies are primary antibodies, which are directly conjugated to fluorescent dye.
39. Into how many types is immuno fluorescence is divided?
Immuno fluorescence is divided into 2 types-
1. Direct immuno fluorescence
2. Indirect immuno fluorescence
40. What are the most commonly used fluorescent dyes?
The most commonly used fluorescent dyes are fluorescin or rhodamine. Both dyes can be conjugated to Fc region of antibody without affecting the specificity of the antigen.
41. What is immuno fluorescence?
Fluorescence is the property of absorbing light ray of particular wavelength and emitting rays in different wavelength.
Antigens that are bound to cells or tissue sections can be visualized by tugging the antibody molecule with a fluorescent dye or fluorochrome.
42. Give application of counter current immuno electrophoresis
This technique is applied to detect the antibody against hepatitis-B and to detect antibodies against SLE (systemic leupus erythromotosis) and used to detect specific antigen foe- meningo coccus in cerebrospinal fluid.
43. What is counter current immuno electrophoresis?
This technique involves the simultaneous electrophoresis of antigen and antibody in the gel in the opposite direction resulting in precipitation of point where there is optimum concentration of antigen-antibody.
This method produces visible precipitin with in 30 minutes and is 10 times more sensitive than the standard double diffusion technique.
44. Give some applications of immuno electrophoresis.
1. This technique is useful for testing normal and abnormal proteins in serum and urine.
2. It is useful to determine whether a patient produces abnormally a low amount of one or more proteins.
3. It is also used if a patient over produces some serum proteins.
45. How is immuno electrophoresis more advance than paper electrophoresis?
In paper electrophoresis, serum proteins can be separated into 5 different bands but the same protein using immuno electrophoresis can be separated into 30 different proteins.
46. What is immuno electrophoresis?
The resolving power of immuno diffusion was greatly enhanced bye immuno electrophoresis. This involves the electrophoretic separation of antigen into its constituent proteins followed by immuno diffusion.
This technique is performed on 1% agarose gel. Antigen mixture is first electrophori zed and separated based on charge, troughs are then cut in the agarose gel, and antiserum is added to the troughs.
The agarose gel is then incubated 18-24hrs during which the antigen and antibody diffuse towards each other. The formation of precipitin bands can be observed for the individual antigen components.
47. What is double immuno diffusion method?
In this method, both antigens and antibodies diffuse radically from wells towards each other by establishing a concentration gradient. As equivalence is reached, a visible line of precipitation is observed.
The patterns of precipitin lines that are formed when two different antigens are placed in adjacent wells indicate whether they share any common epitope or not.
Identity occurs when two antigens share identical epitopes; hence, the line of precipitation formed by them will fuse to give single curve line of identity.
Non-identity occurs when two antigens are unrelated. The antiserum form independent precipitin lines that cross each other.
Partial identity occurs when two antigens share common epitope. The antiserum forms line of identity with the common epitope and a curved spur with the unique epitope.
48. What is the limitation for radial immuno diffusion method?
This method cannot the antigens present in concentration below 5-10 micro grams/ml.
49. What is radial immuno diffusion method?
It is used to qualitate the antigen. Suitable dilution of antiserum is incorporated in the agar gel. Antigen is added to the wells cut on the surface of the gel. As the antigen diffuses into the agar region, equivalence is established and ring of precipitation is formed. The area of precipitin ring is directly proportional to the concentration of antigen. By comparing the area of precipitin with a standard curve obtained by measuring the precipitin area of known concentration of antigen, the concentration of antigen in the given sample can be determined.
50. Name the two-immuno diffusion techniques.
? Radial immuno diffusion method and
? Double immuno diffusion in two dimensions
51. What are immuno diffusion reactions?
These reactions can be used to determine relative concentrations of antigens and antibodies to compare antigens and to determine the relative purity of an antigen. They are mainly preformed in 1% agarose gels.
52. What are the applications of precipitation reactions?
1. Precipitation reaction is the basic reaction for a number of techniques.
2. It is less sensitive for detecting antibodies.
3. Precipitation reactions in gels have several advantages rather than in liquid medium.
4. They have forensic application in identification of blood and seminal stains.
53. What is zone of equivalence?
In this, ratio of antigen-antibody is seen optimal which results in large multimolecular lattice, hence maximum precipitation is observed.
54. What is zone of antibody excess?
In this, the first available antigen is completely filled by antibody molecules. Hence, no antigenic determinant is left out free. Unreacted antibody is seen in large amount, hence poor lattice formation.
55. What are the three distinct phases that a precipitation shows?
The three distinct phases are
Ascending part called ‘zone of antibody excess’.
A peak called ‘zone of equivalence’.
A descending part called ‘zone of antigen excess’.
56. Give the mechanism of precipitation.
Marrak proposed the lattice hypothesis to explain the mechanism of precipitation.
The amount of precipitate formed is greatly influenced by relative proportions of antigens and antibodies.
The valency of antigens is multivalent.
When antigen-antibody is in optimal concentration, the precipitation is complete. So that, large lattice is formed.
57. Briefly describe about precipitation reaction.
When a soluble antigen combines with corresponding antibody in the presence of electrolyte at a suitable temperature and pH, the antigen-antibody complex forms an insoluble precipitate .Antibodies that form precipitate ate called precipitants.
58. Into how many types is antigen-antibody reactions are broadly classified?
It is broadly classified into five-
1. Precipitation
2. Agglutination
3. Complement fixation
4. Immunoassay using labeled reagents
5. Immunohistrochemistry (Immunoflourescence)
59. What is horseman antigen?
The glycolipid antigens are present in most tissues of guinea pigs but not in the RBC. They are found in gastrointestinal mucosa in some people. This horseman antigen will not induce antibody formation.
60. What are heterophile antigens?
Heterophile antigens are polysaccharides, which are structurally similar because of their limited complexity. They are derived from members of widely separated taxonomic groups.
61. Give an example of cross-reaction.
Cross reactivity is often observed in polysaccharide antigens that contain similar oligosaccharide residue. A, B, O blood group antigens - These are glycoprotein expressed on RBC.
62. What is a cross-reaction?
Antigen-antibody reactions are specific, but in some cases antibody elicited by one antigen can cross react with another antigen. This reaction is called as cross-reaction and the antigen that produces cross-reaction is called as cross-reactive antigen. Cross-reaction is due to the presence of two or more antigenic determinants on the related antigen.
63. What is avidity?
The capacity of an antiserum containing various antibodies to combine with the whole antigen is called avidity. Thus, avidity is used to denote the overall capacity of an antibody to combine with multivalent antigen.
A multivalent antigen has many types of antigenic determinants, when this is injected into the blood each antigenic determinant stimulate the production of particular antibody.
64. What is affinity of an antibody?
The strength of binding of an antibody to a monovalent antigen or single antigenic determinant is called affinity of an antibody.
65. Explain in brief about Vander Val interactions in antigen-antibody interaction.
Temporary transfer of electrons from one molecule to another will result in the force of attraction between them. This is seen when the interacting molecules come close to each other.
66. Explain in brief about hydrophobic interactions in antigen-antibody interaction.
Contribute up to 50% of the total strength of antigen- antibody interactions. These reactions are found when ever the side chains of non-polar amino acids of antigen-antibody come together.
67. Explain in brief about hydrogen bonds antigen-antibody interaction.
Reversible hydrogen bonds are formed between hydrophilic groups such as hydroxyl, amino and carboxylic group. Although hydrogen bonds are relatively weak, they play an important role in interaction of antigen-antibody.
68. Explain in brief about electrostatic bonds in antigen-antibody interaction.
These are formed due to the attraction between opposite charged protein side chains.
69. What are the forces that are responsible for antigen-antibody reactions?
The process that holds antigen-antibody together is called non-specific interactions. Inter molecular forces may be classified into four-
1. Electrostatic bonds
2. Hydrogen bonds
3. Hydrophobic interactions
4. Vander Val interactions
70. What is a paratope?
The portion of the antibody molecule that binds to the epitope is called as paratope. Epitope and paratope determine the specificity of immunological reactions.
71. What is an epitope?
The smallest unit of antigenesity is known as antigenic determinant or epitope.
The part of the antigen at which the antibody reacts is known as epitope or antigenic determinant.
It is a small area possessing specific chemical structure and stereo configuration on the antigen capable of sensitizing on immuno site and of reacting with its complimentary site on the specific antibody.
72. What is antigenic specificity?
Antigen antibody reaction is specific and specificity is determined by special configuration of antigenic determine.
73. Give some general features of antigen-antibody interaction.
1. The reaction is specific and antigen combines only with its corresponding antibody and vice versa.
2. Entire molecules react but not the fragment.
3. There is no denaturation of antigen or antibody during the reaction.
4. The combination of antigen – antibody is firm but reversible. The firmness of the reaction is influenced by the affinity and avidity of the reaction.
5. Both antigens and antibodies participate in the formation of agglutination and precipitation reactions.
6. Antigens and antibodies can combine in various proportions unlike chemicals with fixed valancy.
74. What is an antigen and antibody interaction?
Antigen-antibody interaction is similar to an enzyme substrate interaction. The reaction between antigen and antibody occurs in two stages. Primary stage is the initial interaction of antigen-antibody without any visible effect .The reaction is rapid and obeys the general law of thermodynamics and physical chemistry.
The primary stage is followed by the secondary stage leading to demonstrate events such as precipitation, lysis of cells, neutralization of toxins and fixation of compliments etc.
75. Briefly describe about dosage and route of administration, which make a substance antigenic.
Combination of optical dosage and routes of administration will induce a peak immune response in a given animal. An insufficient dose will not stimulate an immune response. An excessive dose does not give a peak immune response because it causes a state of immunological unresponsiveness or non-response known as immunological tolerance.
76. Briefly, describe about the foreignness of a molecule, which makes a substance antigenic?
To be antigenic macromolecules must come from foreign source. Antigens from related species are less antigenic than that of unrelated species. More distance the antigen source the better is the antigenesity.
Ex: Plant proteins are good antigens in animals, where as duck serum proteins are not good antigens for chick.
77. Briefly describe about the chemical nature of the molecule, which make a substance antigenic.
Most naturally, occurring antigens are proteins and polysaccharides. Lipids and nucleic acids are less antigenic. The antigenic property of these compounds is enhanced by combination with proteins.
Certain degree of structural complexity is required for antigenesity. Synthetic polymers are macromolecules in size are not antigenic because they lack structural complexity. Ex: Gelatin
78. Briefly describe about size of a molecule, which make a substance antigenic.
Molecule size of an antigen has a direct relation to antigenesity. Very large molecules such as haemocyanin (6.7 million Daltons) and thymoglobulin (669 kd) are highly antigenic where as low molecular weight compounds whose molecular weight is less than 10,000 Daltons are poor antigenic. Ex: Insulin and histones
79. What are the factors that influence immunogenesity?
A number of factors have been identified which make a substance antigenic. They are -
? Size
? Chemical nature
? Susceptibility to tissue enzymes
? Foreignness
? Immunogen dose and route of administration
80. Give an example for hapten molecule.
Small molecules such as DNP (Dinitro phenyl), M-amino benzene sulphonate by themselves are not immunogenic. However, when they conjugate with a protein such as Bovine serum Albumin (BSA), they can act as complete antigens.
81. What are haptens?
Haptens are small molecules that can react specifically with antibodies but cannot initiate immune response by themselves. They have property of antigenesity, but lack immunogenicity.
82. What is cell-mediated immune response?
It is based on T cells. These T cells are of two types.
T helper cells (TH)
T cytotoxic cells. (TC)
T helper cells interact with antigen MCH II present on APC (Antigen presenting cell) and secrete cytokines. These activate B cells, Tc cells and other phagocytic cells; these activated phagocytic cells kill microorganisms like protozoa and bacteria.
83. What is humoral immune response?
It is based on antibodies. It is conferred to non-immune individuals by administration of serum antibodies from an immune individual. Antibodies bind to the antigens and facilitate their elimination by forming clusters through cross-linking.
84. What is immunogenesity?
The ability of a material to induce an immune response is referred to as immunogenesity.
85. Into how many types is immune response divided?
Immune response is divided into two types
1. Humoral immune response
2. Cell mediated immune response.
86. What is an immunogen?
The ability of a material to induce immune responses referred as immunogenicity and such material is known as an immunogen.
87. What is antigensity?
The ability of an antigen to combine specifically with the final products of immune response is called as antigensity.
88. What is an antigen?
A substance that can produce a specific immune response when it is introduced into the animals and that can react specifically with the products of immune response is generally known as an antigen.
89. What is opsonisation?
Immunoglobulins specific for particulate antigens such as bacteria play an important role by coating the surface of the bacteria and making the antigen more susceptible for phagocytosis. This process is called as opsonisation.
90. What is Secondary IgA?
It is a dimer of molecular weight of 400,000 Daltons and sedimentation coefficient of 11S.
It contains a glycin rich polypeptide called a secretary component or secretary piece. It is relatively resistant to digestive enzymes and reducing enzymes. It is believed to play an important role in local immunity against respiratory and intestinal pathogens.
91. What is serum IgA?
It is a monomer. It has a molecular weight of 160,000 Daltons and sedimentation coefficient of 7S.
92. Give the classification of IgA.
IgA occurs in two forms.
* Serum IgA
* Secondary IgA
93. Give the classification of IgG.
IgG is again sub divided in 4 sub classes. They are
1. IgG 1
2. IgG 2
3. IgG 3
4. IgG 4
94. Briefly describe immunoglobulin M.
1) It constitutes 5.8% of total immunoglobulins. It has a normal serum level of 0.5 to 2 mg/ml.
2) it is a pentamer having a molecular weight of 900,000 Daltons and has a sedimentation coefficient of 19S. It is phylogenetically oldest immunoglobulin.
3) It has a half-life of about 5 days.
4) 5 monomers are arranged with their Fc fragments in the centre of the pentamer and the antigen binding sites towards the periphery of the molecule.
5) It is the first immunoglobulin to be synthesized by the foetus beginning by about 20 weeks of age.
6) It is 500-1000 times more effective than IgG in opsonization.
7) It particularly gives protection against microorganisms and other larger antigens that have repeating antigenic determines on their surface.
95. Define immunoglobulin D
? Molecular weight of IgD is185, 000 Daltons and has a sedimentation coefficient of 7S.
? Its concentration in serum is about 3 mg/100ml, which constitutes about 0.2% of total Ig.
? It is mostly intra vascular in distribution.
? Its half-life is about 3days.
? It is rich in carbohydrates.
? IgD along with IgM occurs on the surface of unstimulated or mature B cells and serves as a reorganization receptor for antigens.
? No biological effect or function has been identified for IgD.
96. Briefly describe immunoglobulin (Ig) E.
1) It is a monomer having a molecular weight of about 200,000 Daltons and has a sedimentation coefficient of 8S.
2) Its half life is about 2 days
3) Its concentration in serum is very low i.e. 0.3 mg/ml.
4) It exhibits unique property such as heat labiality and affinity for the surface of tissue cells such as mast cells.
5) It does not pass the placental barrier.
6) It is chiefly produced in the linings of respiratory and intestinal tracks.
7) It is responsible for the anaphylactic type of hypersensitivity.
8) The physiological role of IgE appears to be protection against pathogens by mast cells degranulation and release of inflammatory mediators.
9) Interleukin fold enhances the secretion of IgE.
97. Briefly describe Immunoglobulin (Ig) A.
1) It is the second most abundant class containing 10-13% if serum immunoglobulins.
2) It has a half-life of 6-8 days.
3) IgA is actively secreted by mucosal associated lymphoidal tissue (MALT).
4) Its molecular weight is 60,000 Daltons.
5) IgA is synthesized locally by plasma cells and dimerized intra-cellular before secretion, with the help of cysteine rich polypeptide, called the J chain, which has a molecular weight of 15,000.IgA functions by inhibiting the adherence of coated microorganisms to the surface of mucosal cells.
98. Briefly describe Immunoglobulin (Ig) G.
1) This is the major serum Ig containing 75% of the total serum immunoglobulin concentration.
2) It has a molecular weight of 150,000 Daltons and sedimentation coefficient is seven.
3) Its half-life is approximately 23 days.
4) It is the Ig, which is normally transported across the placenta and provides natural passive immunity to the newborn
5) It participates in immunological reactions such as compliment fixation, precipitation, and neutralization of toxins and viruses.
6) It is secreted in large amounts during secondary immune response.
99. What are isotypes?
IgG, IgA, IgM, IgD, IgE classes are variants of immunoglobulin molecule. They are termed as isotypic variants or isotypes.
100. How immunoglobulins are measured?
Immunoglobulins are measured using sedimentation coefficient (measured by Svedberg) or ‘S’ value.
Immunology Multiple Choice Questions and Answers PDF Experienced Freshers
Hypersensitivity is classified into five types-
? 1. Anaphylaxis
? 2. Antibody dependant cytotoxicity
? 3. Immune complex mediated diseases
? 4. Delayed type ‘o’ cell mediated hypersensitivity
? 5. Stimulatory hypersensitivity
2. What is anaphylaxis?
It is most rapid hypersensitive reaction. It responds within minutes of applying a stimulus and can get localize. Reactions are mediated by release of pharmacologically active substances.
3. What is hypersensitivity?
The inflammatory response produced by inflammatory molecules result in tissue damage and some times even death. We call this as hypersensitivity or allergy.
4. What is delayed hypersensitivity?
We can recognize the Symptoms only days after exposure. This is delayed hypersensitivity (DTH).
5. What is a myeloma protein?
It is a monoclonal immunoglobulin produced from a myeloma cell.
6. What is opsonin?
Opsonin is a substance, which promotes phagocytosis of antigens by binding to them.
7. What is an incomplete antibody?
Antibody can bind to an antigen but cannot induce agglutination is called incomplete antibody.
8. What are iccosomes?
The particles coated with immune complexes and are released from follicular dendritic cell extensions, are called as iccosomes.
9. Name the scientists who classified hypersensitivity.
Coombs and Gell
10. What are hypersensitive reactions?
If humoral or cellular immunity is switch on to high for length of time, tissue damage may occur. Such reactions are called hypersensitive reactions.
11. What is auto immunity?
Disease caused by immunological reaction to self-antigen. Such type of diseases is classified either organ specific or non-organ specific.
12. Name some of the immuno suppressive agents.
? Cytotoxic agents such as chlorambucil, cyclophosphamide, and azathioprine
? Glucocorticoids
? Cyclosporine
? Antilymphocyte antibodies
13. What is immuno suppression?
Immuno suppression is particularly given to the patients who are undergoing organ transplantation in the treatment of autoimmunity, graft rejection and in allergy conditions.
14. What are the types in adjuvants?
? 1. Organic adjuvants
? 2. Synthetic adjuvants
? 3. Tuftsin
15. What is an adjuvant?
Adjuvant potentates the immune response Vaccines need to be enhanced by some substances, these substances are called adjuvants.
16. What is vaccination?
Vaccination means exploiting the immune system to protect against infectious diseases. Vaccination is done to protect against lethal diseases such as mumps, rubella, poliomyelitis, diphtheria, tetanus, small pox etc.
17. What is attenuation?
Natural behavior of an organism without causing disease is called attenuation i.e. reducing pathogenesity of the organism.
18. What is secondary immune response?
Secondary immune response occurs when second exposure to the same antigen occurs after weeks, months or after years.
19. What is inductive or latent period?
After immunogen is introduced no antibody is detected, this is latent or inductive period. In this period, immunogen is recognized as a foreign substance.
20. What is primary immune response?
First exposure to an antigen produces primary immune response.
21. What is a binder?
The binding protein (usually antibody) which binds to the ligand is called as binder.
22. What is an analyte or ligand?
The substance whose concentration is to be determined is called as an analyte or ligand.
23. What is importance of radio immuno assay?
It is the most sensitive technique used for detecting antigen or antibody. This type of reaction is also called as binder ligand assay.
24. In radio immuno assay what is the used to label an antigen?
In this technique, the antigen is generally labeled with a- emitting isotopes such as I125.
25. What is radio immuno assay?
It is a competitive binding assay in which fixed amount of antibody and radiolabelled antigen react in the presence of unlabelled antigen.
26. What is western blotting?
Identification of specific protein in a complex mixture of proteins can be accomplished bye a technique that is known as western blotting.
27. What are the enzymes used for labeling of antibodies?
Enzymes used for labeling of antibodies are horseradish peroxidase, alkaline phosphatase, ß- galactosidase, lacto preoxidase, etc.
28. What is the significance of indirect ELISA?
It is used for the detection of the presence of serum antibodies against immuno deficiency virus (HIV, the causative agent of AIDS).
29. In how many ways ELISA can be carried out.
It can be carried out in three ways.
Indirect ELISA
Sand witch ELISA
Competitive ELISA
30. What is the significance of ELISA?
It is used for the detection and for identification of either antigen or antibody.
31. Name two enzymes that have been employed for ELISA.
1. Alkaline, phosphatase, horseradish, preoxidase
2. Para nitro phenyl phosphatase
32. What is the basic principle of ELISA?
The basic principle is an enzyme conjugated to n antibody reacts with a colorless substrate to generate a colored product.
33. What is the full form of ELISA?
Enzyme Linked Immuno Sorbant Assay.
34. What are the uses of indirect immuno fluorescence?
1. For identifying bacterial species
2. Detecting antigen-antibody complexes in autoimmune diseases
3. Detecting compliment components in tissues.
4. Localizing hormones
35. What are the advantages of indirect immuno fluorescence?
The primary does not need to be conjugated with label.
It increases the sensitivity of staining because multiple fluorochrome reagents will bind to each antibody molecule.
This method has great flexibility.
36. What is indirect immuno fluorescence?
In a method the primary unlabelled antibody is detected with a number of reagents have been developed for indirect staining. The most common is fluorescence labeled anti isotype antibody such as fluoroscin labeled goat- mouse antibody.
37. What is the disadvantage of direct immuno fluorescence?
A separate fluorescent conjugate have to be prepared against each antigen to be tested.
38. What is direct immuno fluorescence?
In this method, the species antibodies are primary antibodies, which are directly conjugated to fluorescent dye.
39. Into how many types is immuno fluorescence is divided?
Immuno fluorescence is divided into 2 types-
1. Direct immuno fluorescence
2. Indirect immuno fluorescence
40. What are the most commonly used fluorescent dyes?
The most commonly used fluorescent dyes are fluorescin or rhodamine. Both dyes can be conjugated to Fc region of antibody without affecting the specificity of the antigen.
41. What is immuno fluorescence?
Fluorescence is the property of absorbing light ray of particular wavelength and emitting rays in different wavelength.
Antigens that are bound to cells or tissue sections can be visualized by tugging the antibody molecule with a fluorescent dye or fluorochrome.
42. Give application of counter current immuno electrophoresis
This technique is applied to detect the antibody against hepatitis-B and to detect antibodies against SLE (systemic leupus erythromotosis) and used to detect specific antigen foe- meningo coccus in cerebrospinal fluid.
43. What is counter current immuno electrophoresis?
This technique involves the simultaneous electrophoresis of antigen and antibody in the gel in the opposite direction resulting in precipitation of point where there is optimum concentration of antigen-antibody.
This method produces visible precipitin with in 30 minutes and is 10 times more sensitive than the standard double diffusion technique.
44. Give some applications of immuno electrophoresis.
1. This technique is useful for testing normal and abnormal proteins in serum and urine.
2. It is useful to determine whether a patient produces abnormally a low amount of one or more proteins.
3. It is also used if a patient over produces some serum proteins.
45. How is immuno electrophoresis more advance than paper electrophoresis?
In paper electrophoresis, serum proteins can be separated into 5 different bands but the same protein using immuno electrophoresis can be separated into 30 different proteins.
46. What is immuno electrophoresis?
The resolving power of immuno diffusion was greatly enhanced bye immuno electrophoresis. This involves the electrophoretic separation of antigen into its constituent proteins followed by immuno diffusion.
This technique is performed on 1% agarose gel. Antigen mixture is first electrophori zed and separated based on charge, troughs are then cut in the agarose gel, and antiserum is added to the troughs.
The agarose gel is then incubated 18-24hrs during which the antigen and antibody diffuse towards each other. The formation of precipitin bands can be observed for the individual antigen components.
47. What is double immuno diffusion method?
In this method, both antigens and antibodies diffuse radically from wells towards each other by establishing a concentration gradient. As equivalence is reached, a visible line of precipitation is observed.
The patterns of precipitin lines that are formed when two different antigens are placed in adjacent wells indicate whether they share any common epitope or not.
Identity occurs when two antigens share identical epitopes; hence, the line of precipitation formed by them will fuse to give single curve line of identity.
Non-identity occurs when two antigens are unrelated. The antiserum form independent precipitin lines that cross each other.
Partial identity occurs when two antigens share common epitope. The antiserum forms line of identity with the common epitope and a curved spur with the unique epitope.
48. What is the limitation for radial immuno diffusion method?
This method cannot the antigens present in concentration below 5-10 micro grams/ml.
49. What is radial immuno diffusion method?
It is used to qualitate the antigen. Suitable dilution of antiserum is incorporated in the agar gel. Antigen is added to the wells cut on the surface of the gel. As the antigen diffuses into the agar region, equivalence is established and ring of precipitation is formed. The area of precipitin ring is directly proportional to the concentration of antigen. By comparing the area of precipitin with a standard curve obtained by measuring the precipitin area of known concentration of antigen, the concentration of antigen in the given sample can be determined.
50. Name the two-immuno diffusion techniques.
? Radial immuno diffusion method and
? Double immuno diffusion in two dimensions
51. What are immuno diffusion reactions?
These reactions can be used to determine relative concentrations of antigens and antibodies to compare antigens and to determine the relative purity of an antigen. They are mainly preformed in 1% agarose gels.
52. What are the applications of precipitation reactions?
1. Precipitation reaction is the basic reaction for a number of techniques.
2. It is less sensitive for detecting antibodies.
3. Precipitation reactions in gels have several advantages rather than in liquid medium.
4. They have forensic application in identification of blood and seminal stains.
53. What is zone of equivalence?
In this, ratio of antigen-antibody is seen optimal which results in large multimolecular lattice, hence maximum precipitation is observed.
54. What is zone of antibody excess?
In this, the first available antigen is completely filled by antibody molecules. Hence, no antigenic determinant is left out free. Unreacted antibody is seen in large amount, hence poor lattice formation.
55. What are the three distinct phases that a precipitation shows?
The three distinct phases are
Ascending part called ‘zone of antibody excess’.
A peak called ‘zone of equivalence’.
A descending part called ‘zone of antigen excess’.
56. Give the mechanism of precipitation.
Marrak proposed the lattice hypothesis to explain the mechanism of precipitation.
The amount of precipitate formed is greatly influenced by relative proportions of antigens and antibodies.
The valency of antigens is multivalent.
When antigen-antibody is in optimal concentration, the precipitation is complete. So that, large lattice is formed.
57. Briefly describe about precipitation reaction.
When a soluble antigen combines with corresponding antibody in the presence of electrolyte at a suitable temperature and pH, the antigen-antibody complex forms an insoluble precipitate .Antibodies that form precipitate ate called precipitants.
58. Into how many types is antigen-antibody reactions are broadly classified?
It is broadly classified into five-
1. Precipitation
2. Agglutination
3. Complement fixation
4. Immunoassay using labeled reagents
5. Immunohistrochemistry (Immunoflourescence)
59. What is horseman antigen?
The glycolipid antigens are present in most tissues of guinea pigs but not in the RBC. They are found in gastrointestinal mucosa in some people. This horseman antigen will not induce antibody formation.
60. What are heterophile antigens?
Heterophile antigens are polysaccharides, which are structurally similar because of their limited complexity. They are derived from members of widely separated taxonomic groups.
61. Give an example of cross-reaction.
Cross reactivity is often observed in polysaccharide antigens that contain similar oligosaccharide residue. A, B, O blood group antigens - These are glycoprotein expressed on RBC.
62. What is a cross-reaction?
Antigen-antibody reactions are specific, but in some cases antibody elicited by one antigen can cross react with another antigen. This reaction is called as cross-reaction and the antigen that produces cross-reaction is called as cross-reactive antigen. Cross-reaction is due to the presence of two or more antigenic determinants on the related antigen.
63. What is avidity?
The capacity of an antiserum containing various antibodies to combine with the whole antigen is called avidity. Thus, avidity is used to denote the overall capacity of an antibody to combine with multivalent antigen.
A multivalent antigen has many types of antigenic determinants, when this is injected into the blood each antigenic determinant stimulate the production of particular antibody.
64. What is affinity of an antibody?
The strength of binding of an antibody to a monovalent antigen or single antigenic determinant is called affinity of an antibody.
65. Explain in brief about Vander Val interactions in antigen-antibody interaction.
Temporary transfer of electrons from one molecule to another will result in the force of attraction between them. This is seen when the interacting molecules come close to each other.
66. Explain in brief about hydrophobic interactions in antigen-antibody interaction.
Contribute up to 50% of the total strength of antigen- antibody interactions. These reactions are found when ever the side chains of non-polar amino acids of antigen-antibody come together.
67. Explain in brief about hydrogen bonds antigen-antibody interaction.
Reversible hydrogen bonds are formed between hydrophilic groups such as hydroxyl, amino and carboxylic group. Although hydrogen bonds are relatively weak, they play an important role in interaction of antigen-antibody.
68. Explain in brief about electrostatic bonds in antigen-antibody interaction.
These are formed due to the attraction between opposite charged protein side chains.
69. What are the forces that are responsible for antigen-antibody reactions?
The process that holds antigen-antibody together is called non-specific interactions. Inter molecular forces may be classified into four-
1. Electrostatic bonds
2. Hydrogen bonds
3. Hydrophobic interactions
4. Vander Val interactions
70. What is a paratope?
The portion of the antibody molecule that binds to the epitope is called as paratope. Epitope and paratope determine the specificity of immunological reactions.
71. What is an epitope?
The smallest unit of antigenesity is known as antigenic determinant or epitope.
The part of the antigen at which the antibody reacts is known as epitope or antigenic determinant.
It is a small area possessing specific chemical structure and stereo configuration on the antigen capable of sensitizing on immuno site and of reacting with its complimentary site on the specific antibody.
72. What is antigenic specificity?
Antigen antibody reaction is specific and specificity is determined by special configuration of antigenic determine.
73. Give some general features of antigen-antibody interaction.
1. The reaction is specific and antigen combines only with its corresponding antibody and vice versa.
2. Entire molecules react but not the fragment.
3. There is no denaturation of antigen or antibody during the reaction.
4. The combination of antigen – antibody is firm but reversible. The firmness of the reaction is influenced by the affinity and avidity of the reaction.
5. Both antigens and antibodies participate in the formation of agglutination and precipitation reactions.
6. Antigens and antibodies can combine in various proportions unlike chemicals with fixed valancy.
74. What is an antigen and antibody interaction?
Antigen-antibody interaction is similar to an enzyme substrate interaction. The reaction between antigen and antibody occurs in two stages. Primary stage is the initial interaction of antigen-antibody without any visible effect .The reaction is rapid and obeys the general law of thermodynamics and physical chemistry.
The primary stage is followed by the secondary stage leading to demonstrate events such as precipitation, lysis of cells, neutralization of toxins and fixation of compliments etc.
75. Briefly describe about dosage and route of administration, which make a substance antigenic.
Combination of optical dosage and routes of administration will induce a peak immune response in a given animal. An insufficient dose will not stimulate an immune response. An excessive dose does not give a peak immune response because it causes a state of immunological unresponsiveness or non-response known as immunological tolerance.
76. Briefly, describe about the foreignness of a molecule, which makes a substance antigenic?
To be antigenic macromolecules must come from foreign source. Antigens from related species are less antigenic than that of unrelated species. More distance the antigen source the better is the antigenesity.
Ex: Plant proteins are good antigens in animals, where as duck serum proteins are not good antigens for chick.
77. Briefly describe about the chemical nature of the molecule, which make a substance antigenic.
Most naturally, occurring antigens are proteins and polysaccharides. Lipids and nucleic acids are less antigenic. The antigenic property of these compounds is enhanced by combination with proteins.
Certain degree of structural complexity is required for antigenesity. Synthetic polymers are macromolecules in size are not antigenic because they lack structural complexity. Ex: Gelatin
78. Briefly describe about size of a molecule, which make a substance antigenic.
Molecule size of an antigen has a direct relation to antigenesity. Very large molecules such as haemocyanin (6.7 million Daltons) and thymoglobulin (669 kd) are highly antigenic where as low molecular weight compounds whose molecular weight is less than 10,000 Daltons are poor antigenic. Ex: Insulin and histones
79. What are the factors that influence immunogenesity?
A number of factors have been identified which make a substance antigenic. They are -
? Size
? Chemical nature
? Susceptibility to tissue enzymes
? Foreignness
? Immunogen dose and route of administration
80. Give an example for hapten molecule.
Small molecules such as DNP (Dinitro phenyl), M-amino benzene sulphonate by themselves are not immunogenic. However, when they conjugate with a protein such as Bovine serum Albumin (BSA), they can act as complete antigens.
81. What are haptens?
Haptens are small molecules that can react specifically with antibodies but cannot initiate immune response by themselves. They have property of antigenesity, but lack immunogenicity.
82. What is cell-mediated immune response?
It is based on T cells. These T cells are of two types.
T helper cells (TH)
T cytotoxic cells. (TC)
T helper cells interact with antigen MCH II present on APC (Antigen presenting cell) and secrete cytokines. These activate B cells, Tc cells and other phagocytic cells; these activated phagocytic cells kill microorganisms like protozoa and bacteria.
83. What is humoral immune response?
It is based on antibodies. It is conferred to non-immune individuals by administration of serum antibodies from an immune individual. Antibodies bind to the antigens and facilitate their elimination by forming clusters through cross-linking.
84. What is immunogenesity?
The ability of a material to induce an immune response is referred to as immunogenesity.
85. Into how many types is immune response divided?
Immune response is divided into two types
1. Humoral immune response
2. Cell mediated immune response.
86. What is an immunogen?
The ability of a material to induce immune responses referred as immunogenicity and such material is known as an immunogen.
87. What is antigensity?
The ability of an antigen to combine specifically with the final products of immune response is called as antigensity.
88. What is an antigen?
A substance that can produce a specific immune response when it is introduced into the animals and that can react specifically with the products of immune response is generally known as an antigen.
89. What is opsonisation?
Immunoglobulins specific for particulate antigens such as bacteria play an important role by coating the surface of the bacteria and making the antigen more susceptible for phagocytosis. This process is called as opsonisation.
90. What is Secondary IgA?
It is a dimer of molecular weight of 400,000 Daltons and sedimentation coefficient of 11S.
It contains a glycin rich polypeptide called a secretary component or secretary piece. It is relatively resistant to digestive enzymes and reducing enzymes. It is believed to play an important role in local immunity against respiratory and intestinal pathogens.
91. What is serum IgA?
It is a monomer. It has a molecular weight of 160,000 Daltons and sedimentation coefficient of 7S.
92. Give the classification of IgA.
IgA occurs in two forms.
* Serum IgA
* Secondary IgA
93. Give the classification of IgG.
IgG is again sub divided in 4 sub classes. They are
1. IgG 1
2. IgG 2
3. IgG 3
4. IgG 4
94. Briefly describe immunoglobulin M.
1) It constitutes 5.8% of total immunoglobulins. It has a normal serum level of 0.5 to 2 mg/ml.
2) it is a pentamer having a molecular weight of 900,000 Daltons and has a sedimentation coefficient of 19S. It is phylogenetically oldest immunoglobulin.
3) It has a half-life of about 5 days.
4) 5 monomers are arranged with their Fc fragments in the centre of the pentamer and the antigen binding sites towards the periphery of the molecule.
5) It is the first immunoglobulin to be synthesized by the foetus beginning by about 20 weeks of age.
6) It is 500-1000 times more effective than IgG in opsonization.
7) It particularly gives protection against microorganisms and other larger antigens that have repeating antigenic determines on their surface.
95. Define immunoglobulin D
? Molecular weight of IgD is185, 000 Daltons and has a sedimentation coefficient of 7S.
? Its concentration in serum is about 3 mg/100ml, which constitutes about 0.2% of total Ig.
? It is mostly intra vascular in distribution.
? Its half-life is about 3days.
? It is rich in carbohydrates.
? IgD along with IgM occurs on the surface of unstimulated or mature B cells and serves as a reorganization receptor for antigens.
? No biological effect or function has been identified for IgD.
96. Briefly describe immunoglobulin (Ig) E.
1) It is a monomer having a molecular weight of about 200,000 Daltons and has a sedimentation coefficient of 8S.
2) Its half life is about 2 days
3) Its concentration in serum is very low i.e. 0.3 mg/ml.
4) It exhibits unique property such as heat labiality and affinity for the surface of tissue cells such as mast cells.
5) It does not pass the placental barrier.
6) It is chiefly produced in the linings of respiratory and intestinal tracks.
7) It is responsible for the anaphylactic type of hypersensitivity.
8) The physiological role of IgE appears to be protection against pathogens by mast cells degranulation and release of inflammatory mediators.
9) Interleukin fold enhances the secretion of IgE.
97. Briefly describe Immunoglobulin (Ig) A.
1) It is the second most abundant class containing 10-13% if serum immunoglobulins.
2) It has a half-life of 6-8 days.
3) IgA is actively secreted by mucosal associated lymphoidal tissue (MALT).
4) Its molecular weight is 60,000 Daltons.
5) IgA is synthesized locally by plasma cells and dimerized intra-cellular before secretion, with the help of cysteine rich polypeptide, called the J chain, which has a molecular weight of 15,000.IgA functions by inhibiting the adherence of coated microorganisms to the surface of mucosal cells.
98. Briefly describe Immunoglobulin (Ig) G.
1) This is the major serum Ig containing 75% of the total serum immunoglobulin concentration.
2) It has a molecular weight of 150,000 Daltons and sedimentation coefficient is seven.
3) Its half-life is approximately 23 days.
4) It is the Ig, which is normally transported across the placenta and provides natural passive immunity to the newborn
5) It participates in immunological reactions such as compliment fixation, precipitation, and neutralization of toxins and viruses.
6) It is secreted in large amounts during secondary immune response.
99. What are isotypes?
IgG, IgA, IgM, IgD, IgE classes are variants of immunoglobulin molecule. They are termed as isotypic variants or isotypes.
100. How immunoglobulins are measured?
Immunoglobulins are measured using sedimentation coefficient (measured by Svedberg) or ‘S’ value.
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