Inhibition of antigen- and lectin-induced proliferation of rat spleen cells by a Taenia taeniaeformis proteinase inhibitor.

Rat splenic lymphocytes, cultured in vitro for 3 days in the presence of a larval cestode proteinase inhibitor, exhibited a marked suppression of proliferation when stimulated with Con A, PHA, PWM and ovalbumin. Reduced responsiveness was observed over a full range of concentrations of Con A (16-fold), PHA (50-fold), PWM (four-fold) and ovalbumin (16-fold). These results indicated that the inhibitory action could not be overcome by increasing the mitogen or antigen doses beyond optimal levels. This suppressive effect disappeared when the Taenia taeniaeformis proteinase inhibitor was added 20 h after the initiation of culture, suggesting that the inhibitor affects lymphocyte blastogenesis during the early stages of lymphocyte activation.