[Effect of cAMP modifiers on the cytotoxic activity of macrophages]

The effects of various cAMP modifiers on the changes in the intracellular cAMP level and on the coupling of the cAMP system with realization of macrophage cytotoxicity depending on their functional activity were studied. Nonactivated and activated by E. coli polysaccharides peritoneal macrophages of BALB/c mice and macrophage-like cells of J744 mice were incubated in the presence of cAMP modifiers and further assayed for cytolytic and cytostatic activities. Cells of tetraploid strain of Ehrlich carcinoma G10 were used as target cells. Among other modifiers only dibutyryl-cAMP caused a steady increase of the intracellular nucleotide content, whereas methylisobutylxanthine and isoproterenol in combination with methylisobutylxanthine caused only a temporary increase of the cAMP level. Isoproterenol did not induce any appreciable changes in the intracellular cAMP level. All modifiers under study suppressed the cytotoxic activity of macrophages irrespective of the nature of changes in the intracellular cAMP content. It was assumed that cAMP accomplishes a triggering function in the regulation of the cytotoxic activity of macrophages and that the cAMP system is universal in the regulation of cytotoxicity at various functional states of macrophages.