Production of arachidonic acid metabolites by operationally defined macrophage subsets.

The antitumor activity and arachidonic acid metabolism of operationally defined macrophage populations was examined. Macrophages from mice injected with Mycobacterium bovis (strain BCG) or with pyran-copolymer were cytotoxic for tumor cells. The major arachidonic acid metabolite of these cells was PGE2. Neither resident nor elicited macrophages were cytotoxic. However, elicited macrophages as well as macrophages from BCG injected mice inhibited tumor cell growth. The production of arachidonic acid metabolites by elicited cells, while low initially, was followed by a rapid increase in PGE2. The major metabolites of resident cells were PGE2 and prostacyclin. The cAMP:cGMP ratio correlated with the metabolic activity of the cells.