title: Characterization of a monoclonal antibody that defines an immunoregulatory T cell subset for immunoglobulin synthesis in humans.
abstract: This study characterizes a monoclonal antibody (3A1), and partially characterizes the cell surface antigen and the functional peripheral blood T cell subset that it defines. The 3A1 antigen is present on the surface of several human T cell lines (HSB-2, CEM, MOLT-4, and others) in various amounts but is absent from the T cell line YT4E and all human B cell lines tested. Immunoprecipitation of an HSB-2 extract with 3A1 yielded one specific band with a molecular weight of approximately 40,000 in the presence of reducing agent. With directly fluoresceinated 3A1 antibody, fluorescence-activated cell sorter analysis showed that 85% of peripheral blood E-rosette-positive T cells were positive for the 3A1 antigen. After E-rosette-positive cells had been separated into 3A1+ and 3A1- cell suspensions, the 3A1+ cells helped autologous peripheral blood B cell suspensions toward pokeweed mitogen-driven proliferation and intracytoplasmic Ig production, whereas 3A1-T cells did not. Further, addition of 3A1- cells from some but not all normal subjects to cocultures of 3A1+ cells and B cells actively suppressed intracytoplasmic Ig production. However, the 3A1+T cell subset could be activated by concanavalin A to maximally suppress B cell Ig synthesis in vitro. Thus, the 3A1 antibody defines a major functional subject of peripheral blood T cells and should provide a useful marker for the study of human T cell function.
mesh_terms: D000917:Antibody Formation; D000918:Antibody Specificity; D000954:Antigens, Surface / Q000032:analysis*; D002999:Clone Cells / Q000276:immunology; D000939:Epitopes; D006801:Humans; D007518:Isoantibodies; D008211:Lymphocyte Cooperation; D008565:Membrane Proteins / Q000276:immunology; D009194:Myeloma Proteins / Q000276:immunology; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D000939:Epitopes; D007518:Isoantibodies; D008565:Membrane Proteins; D009194:Myeloma Proteins