Alpha-fetoprotein on human peripheral blood lymphocytes does not block complement-dependent lymphocytotoxicity.
Using a direct immunofluorescence assay, we showed that alpha-fetoprotein (AFP) both in purified form and in hepatocellular carcinoma (HCC) sera was capable of binding onto 10-20% of T lymphocytes and 5-10% of B lymphocytes in human peripheral blood when these lymphocytes were preincubated in AFP-positive fluids at 4 degrees C in the presence of sodium azide. But when the preincubation temperature was raised to 37 degrees C, most of the membrane-bound AFP was internalized or shed, and, consequently, less than 3% of the cells showed positive membrane fluorescence. In addition, binding of AFP onto lymphocyte surface membrane and the continuous presence of large amounts of AFP in these lymphocyte cultures did not interfere with the action of cytotoxic antibodies directed against HLA determinants on the lymphocyte surface.
D002478:Cells, Cultured; D003165:Complement System Proteins; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D006680:HLA Antigens; D006801:Humans; D008214:Lymphocytes / Q000276:immunology*; D000509:alpha-Fetoproteins / Q000276:immunology*
D000939:Epitopes; D006680:HLA Antigens; D000509:alpha-Fetoproteins; D003165:Complement System Proteins