Selective inhibition by betamethasone of allergen-induced release of SRS-A from human lung.

Passively sensitized human lung, when incubated with the appropriate allergen, released histamine and slow-reacting substance (SRS-A). Betamethasone sodium phosphate (5-100 microgram/ml), preincubated with the lung overnight, suppressed, in a dose-related manner, the release of SRS-A without having an effect on the release of histamine. Preincubation for only 1 h produced little effect on the release of SRS-A or of histamine. These results may help to explain some of the beneficial effects of glucocorticoids in allergic asthma.