A monoclonal antibody that binds preferentially to human suppressor T cells

A monoclonal antibody termed JM3-3-3A was produced by somatic cell hybridization. The reactivity was assessed by indirect immunofluorescence. JM3-3-3A was reactive with 41% human peripheral blood T cells and 48% non-T cells. Among various human lymphoblastoid cell lines (MOLT 4F, JM, and TALL-1), TALL-l was found not to be reactive with JM3-3-3A. Human peripheral blood T cells fractionated by JM3-3-3A-coated dish panning were submitted to functional studies. JM3-3-3A positive T cells responded to mitogens, concanavalin A and phytohemagglutinin-P much better than JM3-3-3A negative T cells in the presence or absence of adherent cells. JM3-3-3A positive T cells showed suppressor activity and JM3-3-3A negative T cells showed helper activity in pokeweed mitogen-induced Ig production. More than fifty percent of the JM3-3-3A positive T cells were reactive with OKT8 which binds to suppressor/cytotoxic T cells, whereas 18% of JM3-3-3A negative T cells were reactive with OKT8. In addition, immunoprecipitation experiments identified a protein with an approximate molecular weight of 43,000 as a cell surface antigen for JM3-3-3A. Thus, the reactivity of JM3-3-3A showed a wide distribution but human peripheral blood T cells could be dissected functionally by this antibody.