Prolonged treatment with topical glucocorticoids results in an inhibition of the allergen-induced weal-and-flare response and a reduction in skin mast cell numbers and histamine content

Summary The inhibitory effects of topical glucocorticosteroid treatment on the immediate dermal allergic reaction were studied in 10 patients in a double, randomized, placebo‐controlled fashion. The aim was to study whether a prolongation of the treatment time would enhance the inhibitory effect beyond the 30–40% reduction previously reported after I week of treatment, and whether any changes in skin reactivity were accompanied by changes in the level of mast cells or histamine at the challenge site. Allergen and histamine skin‐prick tests were performed on both forearms before the start of the study and after 2 and 4 weeks of treatment with placebo cream on one forearm and with 0.05% clobetasot‐17‐propionate cream on the other. Punch biopsies from the skin treated actively and with placebo were taken after 4 weeks in eight of the patients. The specimens were used for the light‐microscopic evaluation of mast cell density and for the measurement of histamine and protein content. After 4 weeks of treatment we found a reduction in the allergen‐induced weal (72%; P