This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Antibody Generation, Immunoprecipitation and Agglutination Reactions”.
1. Aggregation of which molecules lead to agglutination?
a) Antigens
b) Antibodies and serum
c) Antigens and antibodies
d) Only antibodies
View Answer
Explanation: Combination of antigens with antibodies gives rise to a reaction which is termed as agglutination. This reaction is said to be one of the most important reaction to test the antigens in order to find out the infection carriers. These antigen recognition tests are termed as agglutination tests that can be easily carried out in laboratories. These tests are said to be very important for clinical testing.
2. Which of the following is NOT a type of agglutination reaction?
a) Slide agglutination
b) Active agglutination
c) Passive agglutination
d) Tube agglutination
View Answer
Explanation: Agglutination reactions are performed in several ways like 1) Slide agglutination (serotyping), 2) Tube agglutination (for e.g.: Widal test) and 3) Passive agglutination (also termed as indirect agglutination in which soluble antigens are coated on vehicle particle e.g.: latex particle, RBCs, etc). There is no such way named active agglutination.
3. Antibodies that produce agglutination reactions are called as glutinins.
a) True
b) False
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Explanation: Antibodies that produce agglutination reactions are called as agglutinins. The best results are seen with IgM antibody as compared to IgG antibody. Excess of antibodies also inhibits agglutination reactions. This inhibition is termed as prozone phenomenon. Therefore, the most important factor while carrying our agglutination reactions is to maintain the optimal level of antibodies.
4. To perform latex agglutination, by what should the specimens be treated before testing?
a) Latex solution
b) EDTA
c) Conc. HCL
d) Sodium chloride solution
View Answer
Explanation: To perform latex agglutination, it is recommended that all specimens should be treated by boiling with EDTA (i.e., ethylenediaminetetraacetic acid). This is because, some constituents of body fluid like Rh factor have found to cause false-positive reactions in latex agglutination. Therefore, to avoid this risk, EDTA wash is preferable as it is a chelating agent so that it will deactivate the specimen from causing any side effect.
5. How is the positive result indicated in slide agglutination reaction?
a) Visibility of separate particles
b) Clumping of the particles
c) Colour change
d) Wavelength difference is seen
View Answer
Explanation: Slide agglutination involves the presence of a slide or tile on which a drop of antiserum is added to suspension of antigen under saline conditions. If this results in formation of clumps it indicates the initiation of agglutination reaction. This reaction may take a few seconds depending on the serum used. In other words, we can say that, if we observe clumping or clumped molecules, it results in agglutination reaction.
6. Immunoprecipitation was developed in relation to which of the following mechanism?
a) Supercritical Chromatography
b) Gas Chromatography
c) Reversed Phase Chromatography
d) Affinity Chromatography
View Answer
Explanation: Affinity Chromatography is a traditional mechanism which results in development of immunoprecipitation. This mechanism works under the basis of allowance of sample and other principal solutions to pass through a column. This column comprises of porous resins like agarose. This agarose carries out immobilization of antibody.
7. What is the approximate incubation period for the procedure of Widal test for testing typhoid bacterial cell?
a) 15 minutes at 37°C
b) 30 minutes at 37°C
c) 60 minutes at 35°C
d) 30 minutes at 35°C
View Answer
Explanation: Widal test involves adding a suspension of dead typhoid bacterial cells to a series of tubes containing the patient’s serum, which has been diluted out to various concentrations. The tubes have to be incubated for 30 minutes at 37°C. After the incubation period, they are centrifuged and examined to note the amount of agglutination that has occurred.
8. Which type of agglutination reaction is used routinely for serological diagnosis of typhoid?
a) Tube agglutination
b) Active agglutination
c) Passive agglutination
d) Slide agglutination
View Answer
Explanation: Tube agglutination test is carried out for determining the antibody and its interaction mechanisms. This method is carried out by serial dilutions process where antigen suspension has a fixed volume and it is added to test tubes containing the respective antiserum. Agglutination reaction may occur within few seconds. This reaction mechanism is broadly tested for typhoid diagnosis as well as for typhus fever.
9. Which form of agglutination is used in blood typing?
a) Particle agglutination
b) Hemagglutination
c) Latex agglutination
d) Tube agglutination
View Answer
Explanation: Hemagglutination is used in blood typing. Agglutination reactions are routinely performed to type red blood cells. In typing for the ABO antigens, RBCs are mixed on a slide with antisera to the A or B blood group antigens. If the antigen is present on the cells, they agglutinate, forming a visible clump on the slide. Determination of which antigens are present on donor and recipient blood is the basis for matching blood types for transfusions.
10. Latex test is popular to detect antigen of which fungus?
a) Cryptococcus neoformans
b) Basidiomycetes
c) Blastocladiomycota
d) Hypomycetes
View Answer
Explanation: Latex tests are very popular in clinical laboratories to detect antigen to Cryptococcus neoformans in CSF or serum and to confirm the presence of beta-hemolytic streptococcus form the culture plates. Latex tests are also available to detect Streptococcus agalactiae, Clostridium difficile toxins A and B and rotavirus. Control latex (coated with antibody form the same animal species from which the specific antibody was made) is tested alongside the latex. In some cases, if the patient specimen or the culture isolate reacts with both the test and control latex, the test is considered non-specific and as a result of this, the result can be difficult to be predicted.
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