A structural/functional domain on human CD36 is involved in the binding of anti-Nak(a) antibodies.
The human CD36 antigen is an integral membrane glycoprotein expressed by platelets, monocytes, endothelial cells and various tumor cell lines. CD36 acts as a receptor for thrombospondin, collagen, Plasmodium falciparum-infected erythrocytes and oxidized low-density lipoprotein. Individuals possessing the Nak(a)-negative phenotype do not express CD36 and risk developing anti-CD36 isoantibodies upon blood transfusion or during pregnancy. In the present study, we have examined the interaction of an anti-Nak(a) serum with recombinantly expressed CD36. Results obtained show that five functional CD36 monoclonal antibodies (OKM5, FA6-152, L103, ESIV-C7 and 10/5) prevent the binding of the anti-Nak(a) serum whereas a single monoclonal antibody (13/10) has no effect. Consistent with this result, an epitope map of CD36 generated using cross-blocking experiments, indicates that the inhibitory monoclonal antibodies recognize closely-related epitopes whereas 13/10 reacts with a distinct CD36 determinant. Furthermore, we have demonstrated, in a recent study, that OKM5, FA6-152, L103 and 10/5 bind to the same CD36 domain defined by amino acids 155 to 183. Taken together, our results indicate that the 155-183 sequence is important for the binding of the anti-Nak(a) serum to CD36 and may represent a surface-exposed, immunogenic and presumably functional region on human CD36.
Daviet
L
L
INSERM Unit 331, Faculty of Medicine Alexis Carrel, Lyon, France.
Morel-Kopp
M C
MC
Kaplan
C
C
McGregor
J L
JL
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism; D000937:Antigen-Antibody Reactions; D015703:Antigens, CD / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D016824:Antigens, Human Platelet / Q000276:immunology*; D001667:Binding, Competitive; D018955:CD36 Antigens; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D018076:DNA, Complementary / Q000235:genetics; D000939:Epitopes / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007106:Immune Sera; D007518:Isoantibodies / Q000276:immunology* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D016824:Antigens, Human Platelet; D018955:CD36 Antigens; D018076:DNA, Complementary; D000939:Epitopes; D007106:Immune Sera; D007518:Isoantibodies; C062601:Naka isoantigen, human; D011994:Recombinant Proteins