Interferon-gamma in the treatment of atopic dermatitis: influence on T-cell activation

Atopic dermatitis (AD) is a chronic relapsing skin disease characterized by various immunologic abnormalities. Its pathogenesis remains obscure and its treatment difficult. We have studied the efficacy of systemic recombinant human interferon-gamma (rhIFN-gamma) treatment (0.05 mg/m2 sc on 3 consecutive days, during 4 weeks) in 10 patients with severe AD. Marked clinical improvement was observed starting from the third week of treatment. Erythema, dryness, and lichenification were the most responsive symptoms. Serum immunoglobulin E and IgG4 levels did not change during treatment. Blood eosinophil count decreased only transiently at the end of the first and second series of injections (days 4 and 11; P = 0.02). Patients with AD showed an increase in CD25-positive cells (11.0% vs 4.88%; P = 0.0001) as compared to 10 age-matched healthy controls. Moreover, in parallel with clinical improvement, a distinct decrease in CD25-positive lymphocytes was observed on days 32 and 50 (P = 0.002 and P = 0.006, respectively). We suggest that in AD the beneficial effect of rhIFN-gamma might be related to the inhibition of excessive T-cell activation, perhaps of the subpopulations, producing interleukin (IL)-4 and IL-5.