Other Blood Groups

There are a variety of other blood group antigens that may occur. More than 200 antigens from 30 other blood groups are known currently. Antibodies to these blood groups generally occur only through exposure during transfusion or pregnancy.

Dosage Effect

• Difference in antibody reaction strength based on the composition of antigen present (e.g., Anti-Jk^a will react more strongly with Jk^a Jk^a RBCs (double dosage) than with Jk^a Jk^b (single dosage)).

Dosage

Rh	Duffy	Kidd	MNSs
-C	-Fya	-Jka	-M
-E	-Fyb	-Jkb	-N
-c			-S
-e			-s

Enzyme Effects

• Can enhance or suppress antigen-antibody binding
  • Inhibits negative charge on cell membrane and denatures enzymes
  • Or, reduces zeta potential to enhance agglutination
• Proteolytic enzymes include ficin, trypsin, papain, and bromelin

Destroyed	Enhanced
Duffy	Rh
MNSs	Kidd
	Lewis

Lewis System

• Antigens are produced within tissues on the type 1 precursor chains, and then absorbed onto RBC membrane
• Le gene located on chromosome 19
  • Dominant gene
• Antigens are either Le^a or Le^b
  • If non-secretor, then Le^a (must have sese secretor gene)
  • If secretor, then Le^b (must have at least one Se secretor gene)
    • Le^a and Le^b antigen present, however most Le^a is converted to Le^b
    • Little-to-no Le^a is absorbed onto red cell membrane, mostly just Le^b
• Generally don't cause transfusion reactions (IgM)
• Not fully developed at birth, so typing may vary until ~6 years old
• Phenotyping can also change during pregnancy

System	Antigen	Antibody	Clinical Relevance	Class	Temperature	Antigen Prevalence
Kell		Anti-K	Important antibody Most immunogenic after D antigen Red cell immunity Associated with transfusion reactions and HDFN	IgG, some IgM	37	<10% Kell positive
		Anti-k	Rare (high frequency antigen)
		Kpa Kpb
		Jsa Jsb
McLoed
Duffy	Fya		Fy negative provides resistance to malaria Certain genotypes (GATA1 mutation) don't produce Anti-Fyb and can receive Fy(a-b+) blood
	Fyb

ABBA PHI LeMiN - IgM antibodies

Duffy'S Kidds R OK - IgG antibodies

Clinically Significant Antibodies

Anti-A and Anti-B

Anti-D

Other Rh Antibodies (Anti-C, Anti-E, Anti-c, Anti-e)

Anti-K