Inhibition of mixed-lymphocyte reaction by quinine and lack of effect on plaque-forming cells and lymphoid-derived tumor cells.

Using Balb/c cells as responder cells and mitomycin-treated C57B1 cells as stimulator cells, it was found that quinine was inhibitory in a one-way mixed-lymphocyte reaction. Incorporation of [3H]-TdR was brought down to base levels in the presence of quinine. Quinine was not toxic for antibody-forming cells, and had no effect on plaque-forming cells formed by antibody-committed cells. The degree of [3H]-TdR incorporation of MOPC-315 tumor cells and Burkitt's lymphoma cells was not affected by the presence of quinine in the medium. The cytotoxicity of quinine for mitogen-stimulated cells was demonstrated in soft-agar cultures.