Inhibition of histamine release from basophil leucocytes of asthmatic patients treated with corticosteroids.

We studied the protective effect of corticosteroids in asthmatic patients both in vivo and in vitro. Steroid treatment of patients inhibited the in vivo response to bronchial challenge with the specific allergen as shown by the substantial rise in allergen-threshold. It also produced inhibition of the in vitro elicited release of histamine and slow-reacting substance of anaphylaxis from blood leucocytes. This effect was apparent within 24 h of starting treatment with prednisolone in a daily dose of 30 mg, and reached a maximum after 48 h. In addition, in peripheral venous blood basophil count and total leucocyte histamine content were reduced, eosinophils disappeared and neutrophils increased.