Protease inhibitors reduce mitogen induced lymphocyte stimulation.

Proteolytic events might play a role during lymphocyte activation. Mouse spleen cells were therefore stimulated in serum-free cultures by PHA, ConA, LPS and dextran sulphate and the effect of various added protease inhibitors on [3H]-thymidine incorporation investigated. Both soybean inhibitor and Trasylol inhibited the response of the cells to all mitogens. The other inhibitors (antipain, leupeptin, ovomucoid, alpha-1 trypsin, alpha-2 macroglobulin) had little or no effect. The marked inhibitory effect of tosyl-lysine chloromethylketone could be neutralized by reduced glutathione, indicating an effect on intracellular glutathione rather than on proteases.