Functional characteristics of human T-cell subpopulations distinguished by a monoclonal antibody

In animals and in man, diverse immunologic functions are mediated by specialized T-cell (thymus-derived lymphocyte) subsets that are distinguishable from one another on the basis of differences in cell surface determinants. Unfortunately, in humans, subset-specific antibodies have been difficult to generate. In this study, production of a murine monoclonal antibody specific for a subset of human T cells was achieved by fusing a sensitized B cell (bone marrow-derived cell) with a myeloma cell and isolating the antibody secreted by the resultant hybrid clone. This antibody binds 30-35% of peripheral T lymphocytes (T(a) (+) cells) but fails to bind remaining T lymphocytes (T(a) (-) cells), B lymphocytes, or monocytes. T(a) (+) and T(a) (-) subpopulations were separated with a fluorescence-activated cell sorter and their in vitro responses to various stimuli were assessed. T(a) (+) and T(a) (-) cells respond equally well to soluble antigens, allogeneic B cells, and autologous B cells, but only T(a) (+) cells respond to concanavalin A. T(a) (+) cells cultured in the presence of concanavalin A gradually lose the T(a) marker, an effect not observed after stimulation with phytohemagglutinin, soluble antigens, or alloantigens. These results suggest that the functional subpopulation of T cells defined by T(a) does not correspond to any previously described human T cell subset. Furthermore, somatic cell hybridization has been shown to be a feasible method for production of monoclonal antibodies specific for subpopulations of human lymphocytes.