Module 2

Question 1

The presence of immune antibodies can be due to:

Answer 1

Pregnancy or transfusion

Question 2

Prozone

Answer 2

Excess of antibody

Question 3

Postzone

Answer 3

Excess of antigen

Question 4

Factors which affect agglutination

Answer 4

Antigen-antibody ratio
Physical characteristics of the antigen
Antibody size
In vitro conditions
Enhancement media

Question 5

Physical characteristics of an antigen which affect agglutination

Answer 5

Number of antigen sites on the RBC
Projection of antigen from RBC membrane
Proximity of antigen sites on the RBC

Question 6

IgG antibodies react best at what temperature?

Answer 6

37C

Question 7

IgM antibodies react best at what temperature?

Answer 7

22C or below

Question 8

Why does centrifugation enhance agglutination?

Answer 8

It counteracts the natural repulsive forces of RBCs to help bring them closer together

Question 9

First stage of agglutination

Answer 9

Sensitization

Question 10

Second stage of agglutination

Answer 10

Formation of an antigen-antibody lattice

Question 11

If rouleaux is suspected, what technique can be used to disperse the stacking of RBCs?

Answer 11

Saline replacement

Question 12

Mixed field

Answer 12

Large agglutinates interspersed with free RBCs (cloudy)

2 populations of RBCs

Question 13

Saline reactive antibody

Answer 13

Produces visible agglutination when reacted with RBCs that have been suspended in saline
Usually IgM

Question 14

Another name for saline reactive antibodies

Answer 14

Complete antibodies

Question 15

Temperature for reaction of saline reactive antibodies

Answer 15

Usually at cold temperatures (4-22C), but may require incubation at 37C to be detected

Question 16

Example of saline reactive antibodies

Answer 16

Anti-A and anti-B antisera used to do forward ABO groupings

Question 17

An example of an IgG saline reactive complete antibody

Answer 17

Anti-human globulin (directed against other IgG antibodies)

Question 18

Non saline-reactive antibodies

Answer 18

Do not produce agglutination in a saline test medium

Usually IgG

Question 19

Another name for non saline-reactive antibodies

Answer 19

Incomplete antibodies