Question

A radial immunodiffusion test is run for 72 hours. The concentration of the antigen is then calculated using the:

A. radius of the precipitation ring.

B. diameter of the precipitation ring.

C. square of the diameter of the precipitation ring.

D. log of the diameter of the precipitation ring.

In immunofixation electrophoresis, antibody is:

A. distributed uniformly throughout the gel.

B. applied on the top surface of the gel.

C. added to troughs cut into the gel.

D. driven through the gel by application of electrical current.

Which of the following is characteristic of a passive agglutination test?

A. The antigen is naturally found on particles.

B. Antigen molecules are artificially bound to particles.

C. Antibody is attached to particles.

D. The antigen–antibody reaction is competitive (no agglutination indicates a positive result).

The particle-counting immunoassay method counts the number of:

A. agglutinated particles.

B. free antibody molecules.

C. free latex particles.

D. antigen–antibody bonds.

If an Ouchterlony immunodiffusion pattern shows an arc equidistant between antigens A and B, this indicates that the antigens:

A. are identical.

B. are entirely different.

C. share a common epitope, with A being a more complex antigen.

D. share a common epitope, with B being a more complex antigen.

If crossed lines result in an Ouchterlony immunodiffusion reaction with antigens A and B, this indicates that antigens A and B:

A. are identical.

B. are entirely different.

C. share a common epitope, with A being a more complex antigen.

D. share a common epitope, with B being a more complex antigen.

A patient's serum sample is added to a solution containing particulate antigen, but no agglutination is observed. What should be done next?

A. Perform serial dilutions of the sample.

B. Report out as a negative test.

C. Add more particulate antigen.

D. Read the reaction in dim light.

The visibility of an agglutination reaction involving IgG can be enhanced by adjusting which factor?

A. Changing to a colder temperature

B. Diluting out the particulate antigen

C. Decreasing the light to read the reaction

D. Adding anti-human Fc

Answer 1

Answer: square of the diameter of the precipitation ring

(A radial immunodiffusion test is run for 72 hours. The concentration of the antigen is then calculated using the square of the diameter of the precipitation ring.)

Answer: applied on the top surface of the gel

( This test is used to recognize the abnormal bands that can be seen on the protein electrophoresis. )

Answer: Antibody is attached to particles.

Answer: antigen–antibody bonds.

( The counts indicate the large amount of the antigen presence.)