TABLE 1 Blood group antigens of African origin

Blood group

African

European

Comment

Ref(s).

Duffy negative [Fy(a- b-)]

≈100% (W. Africa)

0%

Chemokine receptor; P. vivax receptor

30, 31, 32, 33

Glycophorin Dantu

4%

0%

P. falciparum receptor; hybrid glycophorin (extracellular glycophorin B, transmembrane and cytoplasmic glycophorin A)

34

Glycophorin B negative (S- s- U-)

20% (Pygmies)

0%

P. falciparum receptor

35

Sl(a-)

30% (in USA)

1%

Polymorphism in complement receptor 1 (CR1)

36, 37

Rh (V+)

40%

0%

13 transmembrane loops (function unknown)

38, 39

Jsa

17% (in USA)

1%

Zinc metalloendopeptidase-like

40, 41

change our strategy for vaccine development in endemic areas where improved survival is the goal.

BLOOD GROUPS AND MALARIA

There are blood group differences between African Americans and Caucasian populations (Table 1). Sl(a-), which is found in 50% of African Americans, is rare in Caucasian populations. Sl(a-) is a polymorphism in the erythrocyte CR 1 receptor for C3b/C4b (36). It is thought that this receptor is involved in clearing immune complexes from the circulation and may be related to the 4-fold increase in systemic lupus in African Americans. We have been unable to find any reduced invasion of these erythrocytes. Although I still believe it was selected by malaria, I have been unable to find the connection.

Africans also have a high frequency of Rh and Kell antigens that differ from those found in Caucasians (38, 40). One of the genes encoding Rh has recently been cloned, and it is predicted to cross the membrane 13 times (39). Although the function of Rh remains a mystery, it is possible that it may be involved in membrane transport or membrane integrity and may affect survival of the intraerythrocytic parasite.

From the parasite's point of view, certain blood group antigens on the erythrocyte surface are receptors for the attachment and invasion of the erythrocyte. Mutations in these surface proteins in Africans were selected for by resistance to invasion of erythrocytes by malaria parasites.



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