ABO, Rh, and Other Blood Group Systems

ABO system antigens

A, B, H, A1, and A2 antigens.

ABO antibody class

IgG and IgM immunoglobulins.

Bombay phenotype (hh)

Lack of H antigen; types serologically as group O.

Role of H antigen

Serves as the essential site for attaching A and B sugars.

ABO groups with highest and lowest H antigen

Group O has the most H; group A1B has the least.

Se (secretor) gene function

Allows expression of A, B, H, and Leb antigens in body fluids.

Lewis (Le) antigens origin

Plasma antigens that adsorb onto red blood cells as an individual matures.

Forward typing definition

Testing patient red cells using reagent Anti-A, Anti-B, and Anti-D.

Reverse typing definition

Testing patient serum using reagent A1 and B red cells.

Red cell causes of ABO discrepancies

Rouleaux (unwashed cells), mixed fields, subgroups, Bombay phenotype, or leukemia/bacteria.

Serum causes of ABO discrepancies

Rouleaux (high protein), cold antibodies, age (newborn/elderly), or compromised immunity.

Phenotype vs. Genotype

Phenotype is the observable physical expression; genotype is the genetic makeup.

D antigen significance

Most immunogenic Rh antigen; causes HDFN and transfusion reactions.

Antithetical Rh antigens

C is antithetical to c; E is antithetical to e.

Fisher-Race Rh antigens

D, d, C, c, E, and e.

Wiener shorthand: R1

DCe

Wiener shorthand: R2

DcE

Wiener shorthand: R0

Dce

Wiener shorthand: r

dce

Weak D testing principle

Detects small amounts of Rh D antigen on red blood cells.

Weak D testing interpretation

Agglutination at the AHG phase indicates a positive weak D status.

Rh antibody class

IgG; clinically significant because they cross the placenta.

Lewis system characteristics

IgM class, Lea and Leb antigens, reacts at cold/room temperature.

I and i antigen expression

Infants are i-positive/I-negative; adults are i-negative/I-positive.

I system disease association

Cold agglutinin disease (CAD).

P system characteristics

IgM class, cold-reacting, associated with Paroxysmal Cold Hemoglobinuria (PCH).

MNSs system phase and dosage

MN is IgM (cold); Ss is IgG (warm). Often shows dosage.

U antigen characteristics

IgG class, reacts at warm temperatures, causes severe HTR and HDFN.

Kell system characteristics

IgG class, reacts at warm temperatures, causes severe HTR and aggressive HDFN.

Kidd system clinical danger

IgG class; causes delayed hemolytic transfusion reactions with sudden intravascular hemolysis.

Duffy system malaria resistance

Fy(a-b-) phenotype is resistant to Plasmodium vivax malaria.

Lutheran system (Lua vs. Lub)

Lua is IgM/IgG (room temp); Lub is IgG (warm temp).