ENDOGENOUS INTERLEUKIN-10 PREVENTS APOPTOSIS IN MACROPHAGES DURING SALMONELLA INFECTION

To elucidate the biological roles of endogenous interleukin 10 (IL-10) in macrophage responses during bacterial infection, we examined in vi tro effects of neutralizing IL-10 by anti-IL-10 monoclonal antibodies (mAb) on apoptosis of the peritoneal macrophages following Salmonella choleraesuis infection. Marked increments of TNF-alpha production were observed in the culture supernatant later than 6 h after in vitro cul ture with anti-IL-10 mAb. These macrophages succumbed to apoptosis at this stage accompanied by marked increment of IL-1 release, despite th e expression of higher amount of endogenous heat shock protein 70, an inhibitor of TNF-alpha-mediated apoptosis. These results suggest that endogenous IL-10 plays an essential role in protection of Salmonella-i nfected macrophages from autocrine suicide caused by excessive product ion of TNF-alpha after killing of Salmonella. (C) 1995 Academic Press, Inc.