Selective inhibition of the cutaneous late but not immediate allergic response to antigens by misoprostol, a PGE analog: Results of a double- blind, placebo-controlled randomized study

The objective of this study was to investigate the effect of misoprostol on allergen-induced cutaneous immediate- and late-phase allergic reactions in a double-blind placebo-controlled randomized study. We also studied the mechanism of antiallergic effects of misoprostol. A total of 16 dust mite- allergic patients received misoprostol (200 μg) or placebo and then had skin testing on 2 different days. The immediate- and late-phase skin response was monitored for 6 h. Skin biopsy was obtained from 5 selected donors at 5 h. In vitro studies included the effect of misoprostol on eosinophil chemotaxis, eosinophil survival, basophil histamine release, and cytokine production by lymphocytes. All subjects developed an immediate wheal reaction and a late- phase induration in response to dust mite allergens after taking placebo. Misoprostol selectively inhibited the late- but not the immediate-phase response (p < 0.05). Histologic studies revealed a trend toward a reduced number of inflammatory cells in the skin dermis after misoprostol treatment. Misoprostol significantly (p < 0.05) inhibited eosinophil chemotaxis and the production of granulocyte-macrophage colony-stimulating factor by lymphocytes at concentrations ≥ 10^-8 M. However, at significantly lower concentrations (≥ 10^-12 M) misoprostol blocked cytokine-stimulated eosinophil survival. Thus, misoprostol has potent antiallergic effects and blocks the cutaneous late-phase allergic inflammation.