A human T‐cell antigen defined by xenoantiserum to sézary leukemic cells: Immunochemical and functional studies

Xenoantiserum to Sézary cell leukemia cells (ASS) was developed by immunizing rabbits with those cells and was absorbed with human red cells, liver, tonsil B cells, and cultured Raji cells. This reagent reacted by immunofluorescence with virtually all human thymus and T cells. In the thymus, medullary cells reacted more strongly with ASS than did cortical thymocytes. When immunoprecipitates that formed between ASS and 125I‐labeled lymphocyte surface glycoproteins were analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, it was found that ASS precipitated a 72K molecular weight (MW) glycoprotein from T cells but not from B cells. On the one hand, it was shown by functional studies that T cells sensitive to the cytotoxic effect of ASS contained T cells that could aid the immunoglobulin synthesis of B cells induced by pokeweed mitogen. On the other hand, suppressor T cells induced by concanavalin A resided in those cells rather resistant to its cytotoxic effect. These data support the idea that the 72K MW glycoprotein on human thymus and T cells might be homologous to mouse Lyt‐1 antigens.