The anti-anaphylactic and histamine-releasing properties of the antihistamines. Their effect on the mast cells.

IT HAS BEEN SHOWN THAT, DEPENDING UPON THEIR CONCENTRATION, ANTIHISTAMINES ACT IN THREE DIFFERENT WAYS: (a) by competitive inhibition of histamine as already known; (b) by destroying mast cells and releasing histamine; and (c) by preventing mast cell damage and histamine release in anaphylaxis. Furthermore, antihistamines potentiated mast cell damage and histamine release by compound 48/80, when acting on guinea-pig tissues, and inhibited these same phenomena when acting on rat tissues. It is concluded that the effect of antihistamines in anaphylaxis is possibly due both to their competitive inhibition of histamine on smooth muscle receptors and to their inhibition of mast cell damage and histamine release by antigen.