The effects of H1 and H2 receptor antagonism on the response of monkey skin to intradermal histamine, reverse-type anaphylaxis, and passive cutaneous anaphylaxis.

The effects of H1 and H2 receptor anatagonists on models of allergic reactions in monkey skin have been studied. Intradermal histamine is markedly inhibited by H1 receptor antagonists but not by H2 receptor antagonists in the doses used. However, the combination of both receptor antagonists gives greater inhibition than that seen with H1 receptor blockade alone. Reverse-type anaphylaxis is also markedly inhibited by H1 but not H2 receptor antagonists. Passive cutaneous anaphylaxis (PCA) is likewise inhibited by H1 receptor antagonism, but not by H2 receptor antagonism. The combination of the two inhibitors leads to a complete inhibition of this PCA response. The data suggest that the addition of an H2 receptor antagonist may potentiate the effect of H1 blockade alone.