The effects of tacrolimus ointment on regulatory T lymphocytes in atopic dermatitis.

Only very recently studies were conducted in order to evaluate the impact of regulatory T (Treg) cells in the pathophysiology of atopic dermatitis (AD). Nine adult patients with moderate-to-severe AD in riacutization period of a chronic disease were given tacrolimus ointment, while seven hydrocortisone butyrate ointment, that served as controls. We performed lesional-skin biopsies before and after treatment, that were stained immunohistochemically with monoclonal antibodies to CD4, CD25, forkhead/winged helix transcription factor (FoxP3), interleukin (IL)-10 and transforming growth factor (TGF)-beta. CD4+ cells were significantly reduced in post-treatment series. Tacrolimus treatment achieved a significant reduction of CD25+ cells. FoxP3+ cells were present in untreated AD lesions. Both treatments did not significantly modify the number of FoxP3+ cells. The number of IL-10+ cells increased in post-treatment series. Tacrolimus enhanced the production of TGF-beta, while hydrocortisone did not. Restoration of TGF-beta-producing Treg cells may represent another important pharmacodynamic effect of tacrolimus on AD.