The Fc receptor on thymus-derived lymphocytes: II. Mitogen responsiveness of T lymphocytes bearing the Fc receptor.

The responsiveness of purified Fc- and Fc+ T lymphocytes, isolated from normal spleen cell populations by cell sorting on the fluorescence activated cell sorter, has been examined. Although both Fc- and Fc+ T cells responded to phytohemagglutinin, the response to concanavalin A (Con A) was found to be a characteristic of the Fc+ T lymphocyte. The poor responsiveness of the Fc- T cells to Con A was shown not to be due to a requirement of either different concentrations of Con A or for adherent cells. The addition of Fc+ T cells to the Fc- T cells in a ratio of 1:3 resulted in a mitotic response not significantly different from that observed with the purified Fc+ T cells alone and up to 15-fold greater than that of Fc- T cells alone. It is suggested that the Fc T cells can be recruited into mitosis as a result of Con A stimulation of the Fc+ T cells.