RESUMO
Phosphatidylserine, in contrast with other phospholipids, markedly enhanced histamine release from rat peritoneal mast cells induced by dextran or protein antigens. This enhancing effect was selective for dextran and protein antigens and did not extend to the action of compound 48/80 or chymotrypsin. These findings suggest a role for phosphatidylserine in the response of mast cells to antigens.
Assuntos
Liberação de Histamina/efeitos dos fármacos , Fosfatidiletanolaminas/farmacologia , Animais , Antígenos , Quimotripsina/farmacologia , Dextranos/farmacologia , Sinergismo Farmacológico , Técnicas In Vitro , Mastócitos/efeitos dos fármacos , Peritônio/citologia , Fosfatidilcolinas/farmacologia , Fosfatidilinositóis/farmacologia , Fosfolipídeos/farmacologia , Proteínas , Ratos , Soroalbumina Bovina/administração & dosagem , p-Metoxi-N-metilfenetilamina/farmacologiaRESUMO
The opposing actions of phosphatidylserine (PS) and cromolyn on histamine release were studied in rat peritoneal mast cells in vitro. Histamine-releasing drugs could be separated into 2 groups on the basis of whether they were potentiated by PS and inhibited by muM cromolyn (dextran, antigen (BSA), concanavalin A) or neither potentiated by PS nor inhibited by muM cromolyn (48/80, polymyxin, phospholipase C and ATP). Compound 48/80 and polymyxin chemically combined with PS, but this could be circumvented by preincubating the mast cells in PS for one hour, and then washing them free of PS in solution prior to addition of the drugs. These data define at least 2 pathways for induction of histamine release: (1) a PS-potentiated pathway inhibited by muM cromolyn, and (2) a PS-independent pathway unaffected by muM cromolyn. Dose-response curves of the muM cromolyn inhibition of PS-potentiated release revealed a parallel shift, suggesting that cromolyn may compete with PS.