Studies on the steric relationship between HLA antigens, beta 2-microglobulin and the Fc receptor on human platelets.
Normal human platelets were investigated by immunofluorescent staining methods for the steric relationship between HLA class I antigens, beta 2-microglobulin and the Fc receptor. IgG antibody to human class I antigens or beta 2-microglobulin, but not their F(ab')2 fragments, blocked the binding of human IgG-Fc fragments to the platelet Fc-receptor. The receptor binding of human IgG-Fc fragments did not prevent the binding of any of the antibodies. This was observed in incubation studies performed both at 4 degrees C, 20 degrees C and 37 degrees C. The results provide evidence that HLA class I antigens and their associated beta 2-microglobulin are in close proximity to the Fc-receptor on human platelets. It is suggested that inhibition of the platelet Fc-receptor was due to binding between the Fc part of surface-bound antibody molecules and the Fc-receptors.
Endresen
G K
GK
Oslo Sanitetsforening Rheumatism Hospital, Norway.
D001792:Blood Platelets / Q000276:immunology / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D005455:Fluorescent Antibody Technique; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007120:Immunochemistry; D011961:Receptors, Fc / Q000378:metabolism*; D001613:beta 2-Microglobulin / Q000378:metabolism*
D006680:HLA Antigens; D011961:Receptors, Fc; D001613:beta 2-Microglobulin