Indirect Antiglobulin Test (IAT)

Question 1

Two-stage testing procedure designed to detect in vitro sensitization of red cells

Answer 1

Indirect Antiglobulin Testing

Question 2

TRUE or FALSE:
IAT does not require an incubation phase

Answer 2

FALSE - an incubation phase is needed for IAT (but not for DAT)

Question 3

Factors that affect antibody joining to an antigen (5)

Answer 3

-Antigen-antibody ratio
-pH
-Ionic strength
-Temperature
-Time

Question 4

Temperature that IgG usually reacts

Answer 4

37C

Question 5

Temperature that IgM reacts

Answer 5

Room temperature and colder (4C)

Question 6

3 antibody potentiators

Answer 6

-Albumin
-LISS
-PEG

Question 7

Antibody potentiator:
-Has a negative charge at the pH used
-Dissipates the cations around the cell reducing the zeta potential
-Does NOT shorten incubation time (30-60 minutes)

Answer 7

Albumin

Question 8

Antibody potentiator:
-Increases antibody uptake
-Reduces incubation time to 5-15 minutes

Answer 8

LISS

Question 9

Antibody potentiator:
-Removes water thereby concentrating the antibody
-Good for detecting weak antibodies
-Has been known to enhance warm autoantibodies

Answer 9

PEG

Question 10

These can remove the silica acid and therefore the negative charge thus reducing the zeta potential

Answer 10

Proteolytic enzymes

Question 11

What are 2 proteolytic enzymes?

Answer 11

Papain and Ficin

Question 12

Are the following enhanced or inactivated by proteolytic enzymes?:
-Rh
-Kidd
-Lewis
-P
-I
-ABO

Answer 12

Enahanced

Question 13

Are the following enhanced or inactivated by proteolytic enzymes?:
-Duffy
-MNS
-Xga

Answer 13

Inactivated

Question 14

Immediate Spin (IS) or 37C:
-Detect cold IgMs
-May see hemolysis from complement

Answer 14

Immediate Spin

Question 15

Immediate Spin (IS) or 37C:
-Check for agglutination or hemolysis
-Incubation time depends on if LISS or albumin were used

Answer 15

37C

Question 16

3 reasons an IAT should be performed

Answer 16

-Prior to transfusion
-Donors
-Prenatal on mothers

Question 17

What are screening cells?

Answer 17

Group O cells with known antigens

Question 18

-Dirty glassware
-Over-centrifugation
-Over-reading
-Cold autoantibody agglutinating cells before washing
All of these cause what result in the IAT?

Answer 18

False-Positive

Question 19

All of the following can cause what result in the IAT?:
-Inadequate or improper washing of cells
-Antihuman globulin reagent non-reactive owing to deterioration or neutralization
-Antihuman globulin reagent not added
-Serum not added in the IAT

Answer 19

False-Negative

Question 20

False-Negative or False-Positive:
-Cell suspension either too weak or too heavy

Answer 20

False-Negative (prozone or postzone)

Question 21

-Under-centrifuged
-Shaking tube too hard
-Failure to identify a weak positive reaction
All of the above cause what type of result?

Answer 21

False-Negative IAT