Prostaglandin regulation of macrophage function: Effect of endogenous and exogenous prostaglandins

The expression of macrophage antitumor activity and the production of prostaglandins (PG) by operationally defined macrophage populations differed under varying culture conditions. Culture conditions that caused increased PGE 2 production by activated macrophages resulted in an inhibition of their tumoricidal activity. In contrast, production of high levels of PGE 2 by resident and elicited macrophages was associated with an increase in antitumor activity. The activation of resident or elicited cells by lipopolysaccharide (LPS) could be blocked by indomethacin. Treatment of these macrophages with PGE 2 alone also resulted in their activation and subsequent tumor cell destruction. Activation of resident and elicited macrophages by LPS appears to be mediated by PGE 2.