BMS 302: Immunology and Blood Types

What is an antigen?

Protein on RBCs that triggers an immune response.

What is an antibody?

Protein made by plasma cells that binds a specific antigen.

What is whole blood?

Blood with all components (RBCs, plasma, WBCs, platelets).

What are packed cells?

Blood with plasma removed (mostly RBCs).

What does bivalent mean?

Antibody with two antigen-binding sites.

Why are Anti-A and Anti-B called “naturally occurring”?

They form without prior exposure due to bacteria with similar antigens.

What triggers formation of ABO antibodies?

Environmental antigens resembling A/B antigens.

If Anti-A serum causes agglutination, what antigen is present?

A antigen.

If Anti-A serum does not cause agglutination?

No A antigen present.

If Anti-B serum causes agglutination?

B antigen present.

If Anti-B serum does not cause agglutination?

No B antigen present.

What antibody does A serum have?

Anti-B.

What antibody does Anti-A typing serum have?

Anti-A.

What antibody does B serum have?

Anti-A.

What antibody does Anti-B typing serum have?

Anti-B.

What antigen is associated with the Rh system?

Rh (D) antigen.

Rh positive means?

D antigen present.

Rh negative means?

No D antigen present.

Most people are Rh positive or negative?

Rh positive (~85%).

If Anti-Rh serum agglutinates cells?

Rh antigen present (Rh+).

If no agglutination with Anti-Rh serum?

No Rh antigen (Rh−).

Two ways Rh− individuals form antibodies?

1) Rh+ transfusion, 2) Rh+ pregnancy.

Are Rh antibodies naturally occurring?

No.

Cause of erythroblastosis fetalis?

Rh− mother makes anti-Rh after carrying Rh+ fetus.

Treatment for erythroblastosis fetalis?

Exchange transfusion for infant.

Prevention of erythroblastosis fetalis?

RhoGAM injection to Rh− mother.

What do Punnett squares show in blood typing?

Possible offspring blood types from parental genotypes.

Difference between serum and plasma?

Serum = no clotting factors; Plasma = has clotting factors.

Agglutination vs coagulation?

Agglutination = antibody clumping; Coagulation = clot formation.

Rule 1:**

If agglutination occurs → antigen present.

Rule 2:**

No agglutination → antigen absent.

Rule 3:**

Always use known antisera (Anti-A, Anti-B, Anti-Rh).

What does agglutination in cross-match mean?

Incompatible blood.

Type O cells are universal ______?

Donors (cells only).

Type AB individuals are universal ______?

Recipients (cells only).