Effect in man of anti-allergic drugs on the immediate and late phase cutaneous allergic reactions induced by anti-IgE.

Wheal and flare reactions as well as a late cutaneous allergic reaction (LCAR) were induced by anti-human IgE in healthy subjects. The effect of the beta 2-adrenoceptor stimulant terbutaline, the histamine-1 (H1) receptor blocking agent mepyramine and the synthetic glucocorticoid betamethasone on these reactions was studied. All administrations were given intradermally (i.d.). The immediate reaction to anti-IgE was inhibited by 3 micrograms terbutaline and 30 micrograms mepyramine (P less than 0.01) whereas 50 micrograms betamethasone had no effects. Terbutaline had no effect on the flare response induced by i.d. injected histamine but a slight effect on whealing. Terbutaline and mepyramine weakly reduced the LCAR throughout the observation period of 24 h (P less than 0.01). In contrast, betamethasone almost completely abolished the LCAR. It is concluded that the two phases of the skin reaction to anti-IgE are interrelated since an inhibition of the early phase was followed by an attenuation of the LCAR. The mechanism of action of steroids seems to differ fundamentally from that of other anti-allergic drugs since inhibition of the early step in the reaction is not essential to the action on the late step. It is further suggested that terbutaline inhibits anti-IgE-mediated cutaneous reactions by inhibition of the mast cell release reaction.