Eicosanoid Production and Phospholipase A2 Secretion by Peritoneal Macrophages from Rats with Adjuvant-induced Arthritis

The effect of adjuvant-induced arthritis on rat peritoneal macrophage (RPM) function with respect to [14C]arachidonic acid (AA) release, leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) production, and secreted phospholipase A2 (PLA2) activity was investigated. Twice as many cells were lavaged from the peritoneal cavity of arthritic rats 21 days post-adjuvant injection than were lavaged from normal rats. PGE2 production was increased two-fold in Ca++ ionophore-stimulated RPM from the adjuvant animals as compared with RPM from control animals. However, PLA2 secretion, LTB4 production and [14C]AA release were unchanged. These results suggest that PGE2 production, rather than LTB4 production or PLA2 secretion, is preferentially enhanced in Ca++ ionophore-stimulated RPM from arthritic rats and may, therefore, reflect a major role for PGE2 in adjuvant-induced arthritis. However, the presence of increase numbers of macrophages and their associated products, including PLA2 and LTB4, may also contribute to the inflammatory process in this disease.