Blood Typing

Question 1

Discuss the H antigen.

Answer 1

The only antigen in the H blood group system. Has two alleles that are co-dominant but one is much more frequent. H antigen is modified by enzymes encoded by the A or B genes.

Question 2

What are the serum antibodies for A, B, O and hh blood antigens?

Answer 2

Anti B, A, Both, Anti ABO and H

Question 3

Who are the universal blood recipients?

Answer 3

Group AB individuals; They don’t have any ABO antibodies.

Question 4

Who are the universal blood donors?

Answer 4

Group O is the universal donor and the universal plasma recipient

Question 5

What stimulates the development of ABO antibodies?

Answer 5

Bacterial and viral glycolipids and glycoproteins in cell walls, capsids and envelops all have carbohydrate moieties that mimic A and B antigens. The ABO antibodies and gut microbiota develop together.

Question 6

Discuss ABH antigens

Answer 6

Can be detected on embryonic RBCs at 5-6 weeks in utero. Present on all cells except for nervous tissue.

Question 7

Describe the clinical correlation between the secretor gene and Candida albicans.

Answer 7

Soluble ABH antigens (come from secretor genes) are lectins that bind to the surface of glycoproteins on C. albicans; Blocks microbial attachment and colonization. No secretor genes=More infections.

Question 8

Discuss the Rh blood group system.

Answer 8

1. Accounts for the most clinical transfusion reactions.
2. NOT produced in response to normal microbiota.
3. Most Rh- people make IgG antibodies to Rh. Usually happens to Rh-mother giving birth to Rh+ child.

Question 9

Describe Hemolytic Transfusion Reactions.

Answer 9

1. IgG bind to RBCs, Macrophages activated.
2. Cytokines released
3. RBC destruction in liver, spleen. Toxic shock triggered.

Question 10

What are the factors that determine the severity of an HTR?

Answer 10

1. Class of antibody

2. Concentration of antibody

Question 11

Discuss the Coombs Test

Answer 11

Detects plasma antibodies to blood cell antigens or RBCs in cases of hemolytic disease of fetus. Positive sign is agglutination of Fetal RBCs in tube.

Question 12

Discuss an indirect coombs test.

Answer 12

1. To confirm if your patient has circulating antibodies that can bind to non-ABO blood group antigens.
2. If you want to screen a Rh- pregnant patient for anti-Rh antibody.