Organophosphate-induced histamine release from mast cells.

To examine the hypothesis that soman intoxication leads to degranulation of mast cells with the release of histamine, we studied the effects of soman on rat peritoneal mast cells (RPMC) in vitro and in vivo. In vitro studies were performed with RPMC harvested from Edgewood rats, and challenged with soman (10(-8)-3 X 10(-3) M) in Tyrode's buffer. The RPMC exhibited a dose-dependent release of histamine, with maximal release of 50% at 3 to 6 X 10(-4) M. The release process is an active, secretory, noncytotoxic event, which is calcium and temperature dependent, requires metabolic energy and is influenced by intracellular levels of cyclic AMP. We next studied the in vivo effects of disodium cromoglycate (DSCG, 10(-4) M) on soman and Compound 48/80-induced histamine release. In vivo studies were performed by the i.p. injection of 5 ml of Tyrode's buffer containing soman (O-1 LD50), or Compound 48/80 as a positive control, with or without DSCG. The fluid recovered after approximately 10 min in the peritoneal cavity was examined for percentage of histamine release. In vivo, Compound 48/80 induced 49 +/- 1% histamine release, with no inhibition by DSCG (Compound 48/80 plus DSCG induced 49 +/- 0.4% histamine release). On the other hand, soman (1 LD50) induced 17 +/- 5% extracellular histamine release, with complete inhibition by DSCG (soman plus DSCG induced 3 +/- 1% histamine release). The data indicate that soman induced a dose-dependent release of histamine from RPMC, and provide evidence that histamine is a potentially important mediator of the pathophysiological response to organophosphate intoxication.(ABSTRACT TRUNCATED AT 250 WORDS)