SEED EXTRACT OF AEGINETIA-INDICA L INDUCES CYTOKINE PRODUCTION AND LYMPHOCYTE-PROLIFERATION IN-VITRO

We previously reported that the extract of seeds from Aeginetia Indica L (AIL), a parasitic plant, induces potent antitumor immunity in tumo r-bearing mice and that CD4(+) T cells appear to be the main contribut ors in the induction of antitumor resistance. The present study was se t up to investigate the in vitro effects of AIL on various lymphoid ce lls. Spleen cells from mice pretreated with AIL every 2 days for 1 wee k produced interleukin 2 (IL-2), interferon gamma (IFN gamma), tumor n ecrosis factor (TNF) and interleukin 6 (IL-6) when these cells were st imulated in vitro by AIL. Further, we found that CD4(+) T cells were m ain producers of lL-2 and TNF upon the stimulation with ALL in vitro, while both CD4(+) and CD8(+) T cells secreted IFN. On the other hand, ALL was mitogenic in vitro to T enriched splenic lymphocytes as well a s B enriched splenic lymphocytes. Moreover, AIL also proliferated thym ocytes and this activity was potently synergistic with a suboptimal do se of concanavalin A (Con A). Lipopolysaccharide (LPS) contamination i n AIL preparation was negligible since proliferative activity of AIL t o B enriched splenic lymphocytes was not influenced in the presence of an endotoxin antagonist, polymyxin B sulfate (PMB). Further, B cell m itogenic activity of AIL seems to be mediated by different mechanism(s ) from that of LPS since ALL could proliferate B enriched lymphocytes of C3H/HeJ mice which do not respond to the stimulation with LPS. A we ll known biological response modifier (BRM), Krestin (PSK), had no abi lity in inducing either T or B lymphocyte activation in vitro as shown by AIL. Taken together, the in vitro activities of AIL on the inducti on of cytokine production and lymphocyte proliferation might contribut e to the in vivo antitumor effect of AIL.