Control of monocyte C2 production by cyclic AMP.

We have measured the changes in C2 production and in cyclic nucleotide levels in mononuclear leucocytes cultured in the presence of agents which change intracellular cAMP. Adenylcyclase activators, cholera toxin and phosphodiesterase inhibitors increased cAMP levels and reduced C2 production. Imidazole, hydrocortisone and prostaglandin synthetase inhibitors reduced cAMP and increased C2 synthesis. The level of cAMP after 2 hr incubation showed an inverse correlation with C2 levels in the culture supernatants. When histamine, which increases cAMP and reduces C2 production, and imidazole, which reduces cAMP and increases C2 synthesis, were added together, levels of cAMP and C2 did not differ significantly from those found in control cultures. On the basis of these observations we have concluded that changes in monocyte cAMP alter the production of C2.