Selective enhancement of production of IgE, IgG4, and Th2-cell cytokine during the rebound phenomenon in atopic dermatitis and prevention by suplatast tosilate.

BACKGROUND: Atopic dermatitis is a chronic inflammatory skin disease, which is commonly treated with topical steroids. It is, however, associated with rebound after therapy has been discontinued. OBJECTIVE: This study was designed to elucidate the mechanisms of the rebound phenomenon, and to test the effect of an oral anti-allergic medication, suplatast tosilate, on atopic dermatitis. METHODS: This is a randomized, placebo controlled study. Patients with atopic dermatitis who had been treated with strong steroid ointment (dexamethasone valerate) for several years were divided into two groups. One group (the control group, n = 15) was treated with a non-steroid anti-inflammatory ointment (bufexamac ointment), while the other group (the suplatast tosilate group, n = 17) was treated with the anti-allergic medications, suplatast tosilate and bufexamac ointment. In each group, in vitro production of immunoglobulins and cytokines before and after 2 weeks of treatment was measured. RESULTS: In the control group, 15 of the 15 patients experienced rebound and mean production of IgE, IgG4, IL-4, IL-5, IL-10, and IL-13 was enhanced after 2 weeks. In contrast, only 2 of the 17 patients in the suplatast tosilate group experienced rebound. There was no enhancement of production of immunoglobulins and cytokines after 2 weeks of treatment. CONCLUSION: Enhanced production of the Th2-cell cytokines, which selectively induces IgE and IgG4 production, may be involved in the pathogenesis of the rebound phenomenon, and that suplatast tosilate may prevent the rebound phenomenon by down-regulating the production of these cytokines.