INHIBITION AND STIMULATION OF HISTAMINE-RELEASE BY OXATOMIDE

Oxatomide, a histamine H1-antagonist, was also found to inhibit histamine secretion stimulated by allergen and other ligands in a variety of in vitro models: 1. Isolated rat peritoneal mast cells, stimulated to secrete by specific antigen, dextran and concanavalin A; 2. Antigen-stimulated histamine secretion by basophil leucocytes from patients with allergic asthma; and 3. Anti-IgE-induced histamine release from chopped human lung passively sensitized with IgE from allergic asthmatics. Although oxatomide was active in inhibiting histamine secretion stimulated by these various means, it possessed a histamine-releasing effect on its own when used in high concentration, particularly in rat peritoneal mast cells. This effect was less pronounced in human basophils, and was not observed in human lung mast cells. Thus, the inhibition and stimulation of histamine release by oxatomide seemed to be independent actions. © 1979.