Epitopic heterogeneity of the CD36 antigen expressed by normal and neoplastic endothelial cells. An immunohistochemical study with a novel monoclonal antibody 8C9.
Phenotypic and functional heterogeneity of endothelial cells (ECs) is being recognized with increasing frequency. Here we report a novel murine monoclonal antibody (MoAb), named 8C9, that detects a unique epitope on the leukocyte differentiation antigen CD36 (platelet glycoprotein IV or IIIb) expressed by both normal and neoplastic ECs. In immunohistochemical and flow-cytometric studies, 8C9-immunoreactivity was detected on capillary ECs, adipocytes, monocytes, platelets and a human monocytoid cell line U-937, which are known to express the CD36 antigen. Blocking experiments using U-937 cells and studies on cryostat sections revealed that a murine MoAb OKM5, which detects the CD36 antigen, blocked the binding of 8C9 to its antigen. Immunoblot analysis showed that 8C9 bound to a 97-kDa membrane protein expressed by U-937 cells treated with phorbol ester. These results indicate that 8C9 detects the CD36 antigen. However, the findings that some OKM5-positive normal ECs in the liver, spleen and lymph nodes as well as neoplastic ECs in a cutaneous angiosarcoma did not react with 8C9, together with the fact that the CD36 antigen does not form a complex or associate with other proteins, suggest epitopic heterogeneity of the CD36 antigen expressed by these tissues.
D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis*; D018955:CD36 Antigens; D004730:Endothelium, Vascular / Q000276:immunology; D000939:Epitopes / Q000032:analysis*; D006391:Hemangioma / Q000276:immunology; D006394:Hemangiosarcoma / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D009369:Neoplasms / Q000276:immunology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018955:CD36 Antigens; D000939:Epitopes