Stimulatory Effect of IL-10 on Antitumor Cytolytic Activity of Murine Spleen Cells

Joo, Hong Gu

Abstract

L-10 has been recognized as an irnmune suppressive cytokine which inhibits Ag-specific activation and proliferation of T cells. It also inhibits Ag presenting capacity of monocyte/macrophage and down-regulates monokine production. However it has also shown that IL-10 has stimulatory effect on immune effector cells in recent studies. This report shows that IL-10 has direct stimulatory effect on antitumor cytolytic activity suppressed by TGF-B. To assess the effect of IL-10 on cytolytic activity against tumor, spleen cells prepared from tumor-bearing mice were cultured with mitomycin C-treated MOPC-315 cells in the presence of IL-10. Unexpectedly, IL-10 was able to reverse the cytolytic activity suppressed with TGF-B. The stimulatory effect of IL-10 was dependent on the addition time of IL-10. At day 0, 4, those effects were shown higher than those of the other days. Also, the stimulatory effect of IL-10 showed specificity against MOPC-315 tumor cells. To elucidate the role of endogenous IL-10, TGF-B in MLTC cultures, anti-IL-10 and anti-TGF-B mAb were used. The inhibition of IL-10 release in MLTC cultures by using anti-IL-10 mAb resulted in the suppression of cytolytic activity against MOPC-315 tumor cells. Taken together, although IL- 10 has been recognized as a strong immunosuppressive cytokine derived of tumor cells, IL-10 showed the direct stimulatory effect on the antitumor cytolytic activity of spleen cells.