Cytotoxicity of concanavalin A-activated hamster lymphocytes

The ability of hamster lymphoid cells to become cytotoxic in vitro to xenogeneic human cells after stimulation with concanavalin A (ConA) was investigated by using the cell-mediated (51)Cr release test. Cytotoxicity developed by 12 to 16 hr with peak values acquired within 24 hr of stimulation with ConA. The cytotoxicity was found to be mediated by the lymphoid cells themselves rather than by soluble substances. Spleen cells were more efficient than lymph node cells in releasing radioactivity from human cells. The concentration of mitogen was found to be critical in the development of cytotoxicity. ConA concentrations of 12.5 mug or less per culture conferred upon the lymphoid cells the capacity to release (51)Cr from target cells whereas higher concentrations were ineffective and even inhibitory. The cell-mediated cytotoxicity could be reversed by methyl alpha-d-glucopyranoside, but only during the first 8 to 12 hr of stimulation. The lytic reaction did not require the presence of ConA.