Role of the eosinophil in the allergic reactions. II. Release of prostaglandins from human eosinophilic leukocytes.

Human eosinophilic leukocytes respond to a variety of stimuli by liberating an inhibitor of histamine release. The active principle(s) in this eosinophil-derived inhibitor (EDI) was found to be a mixture of acidic lipids of similar physiocochemical behavior and biologic activity to prostaglandins E1 and E2. Indomethacin, an inhibitor or prostaglandin synthesis, specifically blocked the immune release of EDI. The results indicate that stimulation of human eosinophilic leukocytes results in synthesis and release of prostaglandins E1 and E2 from these cells. These findings strongly support the hypothesis that the eosinophil assumes a modulatory role in the allergic inflammatory reaction. The ways by which, under specific antigenic (allergenic) stimulation, human eosinophils could modulate the events asssociated with the allergic response, through the released prostaglandins, are discussed.