INHIBITORY ACTION OF 6-ETHYL-3-(lH-TETRAZOL-5-YL)CHROMONE (AA-344) ON IgE-, IgGa- OR CHEMICAL AGENT-INDUCED HISTAMINE RELEASE FROM ISOLATED RAT MAST CELLS

The antiallergic action of 6-ethyl-3-(lH-tetrazol-5-yl)chromone (AA-344) was studied on isolated rat peritoneal mast cells. AA-344 clearly inhibited the IgE- mediated release of histamine caused by various concentrations of antigen and the 50% inhibitory concentration was 0.1 pM. On the IgGa-mediated release of histamine, a peak inhibition of AA-344 was observed at 10 pM. The histamine release induced by chemical agents such as concanavalin A, dextran and compound 48/80 was depressed by AA-344 at the range of 0.1-1 mM. The results obtained in this study indicate that the antiallergic action of AA-344 is due to selective inhibition on the immunological release of the chemical mediator from mast cells.