Antigen Antibody Reaction And Precipitation Reaction

ANTIGEN ANTIBODY REACTION AND PRECIPITATION REACTION

Q. 1 The reaction that occurs when antibody and soluble antigen are mixed is demonstrated by the
 A Agglutination test               
 B Precipitin test
 C Hemagglutination test       
 D None of the above
Q. 1 The reaction that occurs when antibody and soluble antigen are mixed is demonstrated by the
 A Agglutination test               
 B Precipitin test
 C Hemagglutination test       
 D None of the above
Ans. B

Explanation:

In precipitation test, antibody combines with soluble antigen. While in agglutination test, antibody combines with insoluble antigen


Q. 2

Which of the following is an example of precipitation reaction?

 A

Widal Test

 B

Coomb’s Test

 C

Counter Current immunoelectrophoresis

 D

Weil-Felix Test

Q. 2

Which of the following is an example of precipitation reaction?

 A

Widal Test

 B

Coomb’s Test

 C

Counter Current immunoelectrophoresis

 D

Weil-Felix Test

Ans. C

Explanation:

Precipitation is a method for detecting an antigen–antibody reaction.
When antigen and antibody combine in the proper proportions, a visible precipitate is formed.
Optimum antigen–antibody ratios can be produced by allowing one to diffuse into the other, most commonly through an agar matrix (immunodiffusion). Counterimmunoelectrophoresis (CIE) is a type of precipitation reaction where immunodiffusion carried out in an electrophoretic field.
Both the speed and the sensitivity of immunodiffusion are improved by CIE.
 
Ref: Ray C.G., Ryan K.J. (2010). Chapter 4. Principles of Laboratory Diagnosis of Infectious Diseases. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.

Q. 3

Which of the following statement is true ‑

 A

Paul Bunnell test is used to diagnose measles

 B

Rose Waaler test is a complement fixation test

 C

Indirect hemagglutination test is less sensitive than gel diffusion test

 D

Antigen antibody reaction cannot occur in the absence of electrolytes

Q. 3

Which of the following statement is true ‑

 A

Paul Bunnell test is used to diagnose measles

 B

Rose Waaler test is a complement fixation test

 C

Indirect hemagglutination test is less sensitive than gel diffusion test

 D

Antigen antibody reaction cannot occur in the absence of electrolytes

Ans. D

Explanation:

Ans. is ‘d’ i.e., Antigen Antibody reaction cannot occur in the absence of electrolytes


Q. 4

The reaction between antibody and soluble antigen is demonstrated by –

 A

Agglutination

 B

Precipitation

 C

Complement fixation test

 D

Hemagglutination test

Q. 4

The reaction between antibody and soluble antigen is demonstrated by –

 A

Agglutination

 B

Precipitation

 C

Complement fixation test

 D

Hemagglutination test

Ans. B

Explanation:

Ans. is ‘b’ i.e., Precipitation

Precipitation

. When a soluble antigen combines with its antibody in the presence of electrolytes (NaC1) at a suitable temperature and pH, the antigen – antibody complex forms an insoluble precipitate.

.  When instead of sedimenting, the precipitate remains suspended as floccules, the reaction is known as flocculation.

.  It is very sensitive in detection of antigens and as little as 1 g of protein can be detected by precipitation tests.

.  Precipitation is relatively less sensitive for the detection qf antibodies.


Q. 5

Antigen antibody precipitation is maximally seen in which of the following?

 A

Excess of antibody

 B

Excess of antigen

 C

Equivalence of antibody and antigen

 D

Antigen Hapten interaction

Q. 5

Antigen antibody precipitation is maximally seen in which of the following?

 A

Excess of antibody

 B

Excess of antigen

 C

Equivalence of antibody and antigen

 D

Antigen Hapten interaction

Ans. C

Explanation:

Ans. is ‘c’ i.e., Equivalence of antibody and antigen

  • Precipitation occurs most rapidly and abundantly in the zone of equivalence in which the antigen and antibody are present in optimal proportions.

Q. 6

Reaction of soluble antigen with antibody is known as –

 A

Agglutination

 B

Precipitation

 C

Flocculation

 D

Complement fixation

Q. 6

Reaction of soluble antigen with antibody is known as –

 A

Agglutination

 B

Precipitation

 C

Flocculation

 D

Complement fixation

Ans. B

Explanation:

Ans. is ‘b’ i.e., Precipitation

  • Reaction of soluble antigen          –÷           Precipitation
  • Reaction with particlate antigen –÷             Agglutination

Q. 7

All of the following forces are involved in antigen antibody reaction, EXCEPT:

 A

Vander Waal’s forces

 B

Electrostatic bond

 C

Hydrogen bond

 D

Covalent bond

Q. 7

All of the following forces are involved in antigen antibody reaction, EXCEPT:

 A

Vander Waal’s forces

 B

Electrostatic bond

 C

Hydrogen bond

 D

Covalent bond

Ans. D

Explanation:

Answer is D (Covalent bond) :

The combination between antigen and antibody is effected during the primary stage of an Ag-Ab reaction. This reaction is essentially reversible and effected by the weaker intermolecular forces such as: Vander Waal’s, Hydrogen bonds, Ionic bonds and not by the firmer covalent bonds.

Frequently asked questions on immunoglobulins:

Immunoglobulin to fix complements via classical pathway

Immunoglobulin to fix complements via alternate pathway

Immunoglobulin with maximum serum conc.

Immunoglobulin with minimum serum conc.

Immunoglobulin that in heat labile

Immunoglobulin in primary immune response

Immunoglobulin in secondary immune response

Immunoglobulin with maximum molecular weight

Immunoglobulin present in milk

Immunoglobulin with maximum sedimentation coefficient

Immunoglobulin with shortest 1/2 life

Immunoglobulin in seromucinous glands

Immunoglobulin resp. for hypersensitive pneumonitis

Immunoglobulin mediating the prausnitz Kustner reaction

Homocytotropism is seen in which Ig

IgG & IgM (IgM > IgG)Q

IgAQ & IgDQ

IgGQ

IgEQ

IgEQ

IgMQ

IgGQ

IgMQ

IgAQ & IgGQ

IgMQ

IgEQ

IgG & IgAQ

IgGQ

IgEQ

IgEQ


Q. 8

VDRL is a type of:          

September 2010

 A

Indirect hemagglutination test

 B

Slide flocculation test

 C

Gel precipitation test

 D

None of the above

Q. 8

VDRL is a type of:          

September 2010

 A

Indirect hemagglutination test

 B

Slide flocculation test

 C

Gel precipitation test

 D

None of the above

Ans. B

Explanation:

Ans. B: Slide flocculation test

Venereal Disease Research Laboratory (VDRL) Test is a slide flocculation test employed in the diagnosis of syphilis. Since the antigen used in this test is cardiolipin, which is a lipoidal extracted from beef heart, it is not a specific test. This test is also classified as non-specific or non-treponemal or standard test.

The antibodies reacting with cardiolipin antibodies have been traditionally (but incorrectly) termed “regain”.


Q. 9

Test shown in the photograph below is a type of? 

 A

Indirect hemagglutination test.


 B

Slide flocculation test.

 C

Gel precipitation test.


 D

None of the above.

Q. 9

Test shown in the photograph below is a type of? 

 A

Indirect hemagglutination test.


 B

Slide flocculation test.

 C

Gel precipitation test.


 D

None of the above.

Ans. B

Explanation:

Ans:B.)Slide Flocculation test.

The test shown in the picture above is VDRL.

VDRL

  • Venereal Disease Research Laboratory (VDRL) Test is a slide flocculation testemployed in the diagnosis of syphilis.
    • Since the antigen used in this test is cardiolipin, which is a lipoidal extracted from beef heart, it is not a specific test.
    • This test is also classified as non-specific or non-treponemal or standard test.
    • The antibodies reacting with cardiolipin antibodies have been traditionally (but incorrectly) termed “regain”.
  • VDRLprinciple:
    • When the heat inactivated (to destroy complement) serum of patient is reacted with freshly prepared non-treponemal antigen, flocculation reaction (antigen and antibody complex are suspended) occurs.
    • The flocculation can be observed by using microscope.
    • Reactive VDRL test serum can be quantitated to obtain the titre of “reagin antibodies” by using serial double dilution method.

Q. 10

Identify the Antigen-Antibody reaction in the figure shown in which Lattice hypothesis is used to explain the basis of this reaction . 

 A

Precipitation.

 B

Opsonization.

 C

Complement fixation.

 D

Neutralization.

Q. 10

Identify the Antigen-Antibody reaction in the figure shown in which Lattice hypothesis is used to explain the basis of this reaction . 

 A

Precipitation.

 B

Opsonization.

 C

Complement fixation.

 D

Neutralization.

Ans. A

Explanation:

Ans:A.)Precipitation

 Lattice hypothesis is used to explain the basis of Precipitation.

Precipitation Antigen-Antibody reaction
  • Marrack (1934) proposed the lattice hypothesis – mechanism of precipitation.
  • Precipitation reactions are based on the interaction of antibodies and antigens. They are based on two soluble reactants that come together to make one insoluble product, the precipitate . These reactions depend on the formation of lattices (cross-links) when antigen and antibody exist in optimal proportions.
  • Precipitation curve shows 3 curves:
    • 1.Zone of Antibody excess
    • 2.Zone of Equivalence
    • 3.Zone of Antigen excess
 

Antigen-antibody reaction

  • It is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction.
  • Types of antigen- antibody reactions in vivo:
    • 1. Agglutination
    • 2. Precipitation
    • 3. Complement fixation
    • 4. Neutralization
    • 5. Antibody dependant cell mediated cytotoxicity (ADCC)
    • 6. Immobilization
  • Types of antigen antibody reactions used in vitro:
    • 1. Agglutination
    • 2. Precipitation
    • 3. Neutralization
    • 4. Complement fixation
    • 5. Fluorescent Fluorescent-antibody technique antibody technique
    • 6. ELISA- Enzyme linked immunosorbent Enzyme linked immunosorbent assay
    • 7. Radio immunoassay
    • 8. Immunochromatography (ICT)

 

 



Leave a Reply

%d bloggers like this:
Malcare WordPress Security