Lymphokine and synthesis of complement by guinea pig spleen cells

Lymphokine preparations have been obtained from normal guinea pig spleen cells stimulated in vitro by optimal doses of insoluble Concanavalin A. The biological activity of these preparations was estimated by Macrophage Inhibition Tests performed with peritoneal cells from identical guinea pigs. Addition of these preparations to culture of normal adherent guinea pig spleen cells, gives rise to a dose related inhibition of the normal synthesis of C2, the second component of the complement system, by these latter cells. This inhibition of synthesis, appears to be due to a functional effect of lymphokine on C2-producing cells and not to a cytotoxic effect. Preliminary results indicate that the same lymphokine preparations can have a stimulatory rather than an inhibitory effect on synthesis of haemolytic C1 by the same cells.