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.