Distinction Between Responsiveness of Macrophages to Cyclic-Amp Elevation by Prostaglandin E2and Prostacyclin

Abstract

Macrophages, isolated from carrageenin-induced granuloma (an immune-related inflammatory model), were used to examine the effects of prostaglandin E₂ and prostacyclin on intracellular levels of cyclic-AMP. It appears that during the development of the tissue-growth component of this granuloma in rats the infiltrating mononuclear phagocytes undergo a change, resulting in macrophages which are very sensitive to cyclic-AMP elevation by PGE₂ but insensitive to a similar effect of prostacyclin. Arguments are presented that the difference between the responsiveness of these macrophages to PGE₂ and prostacyclin observed in vitro is directly related to the previously reported distinction between these two metabolites of arachidonate as inhibitors of the carrageenin-induced granuloma in vivo.