Inhibition of the dermal immediate allergic reaction through prolonged treatment with topical glucocorticosteroids.

The effect of prolonged topical dermal glucocorticosteroid treatment on the immediate and late-phase allergic skin reaction was studied in a double-blind, randomized, placebo-controlled study. Seventeen patients with hay fever and with a positive skin test for timothy and/or birch pollen allergens were studied in a pollen-free season. Skin prick tests for these two allergens as well as a negative saline and a positive histamine control were made with a preloaded standardized prick test needle. The area of the induced wheal-and-flare reaction was measured 15 minutes after allergen application, and any induced late-phase responses were measured after 6 hours. After a baseline recording, the patients treated the volar aspect of one forearm twice daily with a cream of 0.05% clobetasol 17-propionate and the other forearm with the equivalent vehicle in a randomized, double-blind fashion. After 1 week the skin prick test was repeated on both arms. A statistically significant reduction of the allergen-induced wheal-and-flare response was found after active treatment as compared to control and pretreatment values. A reduction was also found in the histamine-induced flare but not the wheal reaction as compared to the control. A late-phase dermal reaction was found in six of the patients, and this was statistically significantly reduced by the glucocorticosteroid pretreatment. Thus, in similarity to findings in vivo on the human nose and bronchus, we found, in addition to the well-known glucocorticosteroid-induced reduction of the allergic late-phase response, an inhibition of the dermal immediate allergic reaction as well.(ABSTRACT TRUNCATED AT 250 WORDS)