Distinctive functional characteristics of human „T”︁ lymphocytes defined by E rosetting or a monoclonal anti‐T cell antibody

Abstract The properties of human lymphocyte fractions isolated either by sheep red cell (E) rosetting or by fluorescence‐activated cell sorting after staining with UCHT1 monoclonal anti‐T cell antibody have been compared. Two populations of E + cells with very different phenotype and function have been identified. E + /UCHT1 + cells respond well to the T cell mitogens phytohemagglutinin and concanavalin A and provide help for an in vitro specific antibody response. They can also suppress the antibody response of allogeneic peripheral blood mononuclear cells. In contrast, the E + /UCHT1 − population, which has no other markers characteristic of T cells, fails to respond to mitogens or to provide help or suppression for an antibody response. These cells, however, are highly active natural killers. They possess Fcγ receptors and have a characteristic staining pattern of nonspecific esterase enzyme activity.