Contribution of lymphocytes bearing Fcgamma receptors to PHA-induced cytotoxicity.

Lymphocytes participating in PHA-induced lysis of chicken erythrocytes were characterized by means of cell fractionation methods. Selective depletion of, or enrichment in, E-rosetting cells indicated that the effector cell population was heterogenous, consisting of both T and non-T lymphocytes. Most effector cells, however, were shown to bear Fcgamma receptors detected by the formation of erythrocyte-antibody (EA) rosettes, but to lack C3 receptors. This distribution of effector cells among tonsils, peripheral blood and thoracic duct lymph paralleled that of EA-rosette forming cells but not that of T or B cells. Addition of aggregated IgG resulted in a moderate decrease of PHA cytotoxicity. However, almost complete inhibition was achieved within a few hours of contact between effectors cells and insoluble immune complexes. The results support the hypothesis that cytotoxic capacity is associated with the presence of Fcgamma receptors on the cell surface.