L2. Techniques in blood group serology

Question 1

Explain the agglutination Assay to determine ABO blood group

Answer 1

Red cells suspended in saline. RBCs have + charged cloud around cells, creates repulsive electric potential. Only IgM can cause agglutination in saline.

Question 2

What is tested with anti-A, anti-B anti-A+B with Agglutination Assay?

Answer 2

Anti A: Blood incubated with anti-A, anti-B, anti-A+B.

No agglutination = no A, B or AB antigen.

Question 3

What is tested with A and B cells in Agglutination Assay?

Answer 3

A & B cells tested against RBCs of patients to check if they have Anti cells.
Anti-A & Anti-B present = agglutination.

Question 4

What are the Anti-D test proving in the Agglutination Assay?

Answer 4

Anti-D is added to patient’s RBCs.
If there’s agglutination, it’s D+. No Agglutination, it’s -.
(E.g. AB+, O- etc).

Question 5

Explain the Direct Antiglobulin, or Coomb’s, test (DAT) to detect IgG ABs?

Answer 5

Detects ABs coating the surface of RBCs, in case of hemolytic disease of newborn or hemolytic transfusion reactions.
Blood taken from patient, plasma removed.
ABs added which recognise human ABs coating RBCs. If they recognise it, they agglutinate.

Question 6

Explain the indirect Antiglobulin, or Coomb’s, test (DAT) to detect IgG ABs?

Answer 6

Detects ABs in patient’s plasma.
patient’s serum is taken containing the ABs.
RBC’s from healthy donor are added, the plasma ABs will coat RBCs.
Anti-human IgG is added, which agglutinates the blood.

Question 7

What does agglutination mean?

Answer 7

That the test is positive.

Question 8

What Coomb’s reagent?

Answer 8

Anti-human globulin (AHG)., an AB which recognises human ABs, made inanimals by immunizing. e.g. rabbit with human ABs).