Human lymphocyte antigens: production of a monoclonal antibody that defines functional thymus-derived lymphocyte subsets.

A monoclonal mouse antibody (3A1) that specifically bound to 65% of human peripheral blood (PB) thymus-derived (T) cells but did not bind to complement receptor-positive PB bone marrow-derived (B) cells, polymorphonuclear leukocytes, or human erythrocytes has been produced. The 3AI antibody was synthesized by a stable cloned lymphocyte hybrid cell line. This lymphocyte hybrid line (3AI) was derived from fusion of P3 X 63/Ag8 myeloma cells and spleen cells from BALB/c mice immunized with HSB-2 cells, a human T cell line. The 3A1 lymphocyte hybrid line produced mouse ascites fluid containing 3A1 antibody in saturating titers of up to 1:25,600. Purified PB T cells that carried the 3A1 antigen incorporated tritiated thymidine maximally in response to phytohemagglutinin and concanavalin A stimulation, whereas purified PB T cells that lacked the 3A1 antigen responded suboptimally to phytohemagglutinin and minimally to concanavalin A. Thus, the 3A1 antibody can be easily used to study the role of 3A1-positive and negative T cell subsets in the regulation of normal and abnormal human immune responses.