Effects of modification of intracellularcyclic AMP levels on the imediate hypersensitivity reaction in vivo.

Experiments were performed to study the effects of agents that elevate endogenous cyclic AMP levels on the progression of a reverse passive Arthus reaction in the pleural cavity of rats. Three hours after the onset of the reaction a marked reduction in histamine release was observed which correlated well with increases in cellular cyclic AMP concentration. The results at 6 hr suggested a relationship between cyclic AMP and leucocyte PGE, the latter being reduced dramatically both in the cells and in the fluid exudate by agents that elevate cyclic AMP. It was concluded that cyclic AMP may play an important regulatory role in vivo in the release of inflammatory mediators from leucocytes.