DAT Testing

Question 1

Describe the steps of a DAT test.

Answer 1

Patient red blood cells which may be sensitized by antibody/complement are washed 3 times with saline to remove any residual antibody/globulins.

AHG is added after and incubated at 37C.

If the RBCs are coated in vivo, AHG will react with the IgG antibodies and/or complement and agglutinate (+ DAT).

Question 2

What is the best sample for a DAT test?

Answer 2

EDTA tube

Question 3

What could cause a false positive DAT?

Answer 3

EDTA might chelate Ca++, preventing complement activation

Question 4

What is the purpose of a DAT test?

Answer 4

To determine if hemolysis occurring an immune-dependent (in vivo sensitization) or immune-independent process

Question 5

What is the purpose of adding check cells?

Answer 5

Purpose of check cells is to confirm that AHG is working properly and is bound to all sensitized RBCs (negative check cells result), and that AHG wasn’t neutralized due to insufficient washing

Question 6

What is coating the red blood cells in WARM AUTOIMMUNE HEMOLYTIC ANEMIA (WAIHA) - IgG or complement?

Answer 6

IgG and/or complement

Question 7

What is coating the red blood cells in COLD HEMOAGGLUTINAN DISEASE (CHD) - IgG or complement?

Answer 7

Complement

Question 8

What is coating the red blood cells in Mixed Type AIHA - IgG or complement?

Answer 8

IgG and complement

Question 9

What is coating the red blood cells in Cold Paroxysmal Hemoglobinuria - IgG or complement?

Answer 9

Complement

Question 10

What is coating the red blood cells in Hemolytic Disease of the Fetus and Newborn - IgG or complement?

Answer 10

IgG