Production of cyclooxygenase products and superoxide anion by macrophages in response to chemotactic factors

Abstract

Mononuclear phagocytes are knwon to play a key role in various phlogistic reactions by synthesizing and releasing products that may potentiate or inhibit inflammatory processes. The expression of these products appears to be dependent on the source of the macrophage population as well as the stimulus employed. We have studied superoxide anion (O2-) production as well as the generation of PGE2, PGF2[alpha], and TXB2 from resident, oil-elicited and thiogylcollate-induced peritoneal macrophages in mice in the presence and absence of chemotactic peptides. Production of O2-, occurred only in elicited macrophages stimulated with high concentrations of FMLP or C5a; resident cells stimulated with either of the chemotactic peptides were completely unresponsive. Although resident peritoneal macrophages incubated with chemotactic peptides did not generate O2-, these cells did secrete significant levels of PGE2, PGF2[alpha], and TXB2 in response to C5a. FMLP had no stimulatory effect. Elicited macrophages generated increased levels of PGE2 and PGF2[alpha] when incubated with C5a. However, production of TXB2 was not stimulated. FMLP was inactive in stimulating PGE2, PGF2[alpha], and TXB2 in all types of macrophages studied. These studies indicate a heterogeneity in the production of inflammatory mediators from various macrophage populations in response to chemotactic factors.