Is topical tacrolimus effective in alopecia areata universalis?

SIR, tacrolimus (FK506) is a powerful immunomodulatory macrolide and is used in transplantation medicine to prevent graft rejection. Topical tacrolimus is used successfully in the treatment of atopic dermatitis.1 Similar to cyclosporin, tacrolimus inhibits the activation and maturation of T cells and blocks the transcriptional activation of several lymphokine genes.2,In vitro and in vivo, tacrolimus is about 100 times more effective than cyclosporin.3 Alopecia areata is an autoimmune disease caused by a T‐lymphocytic infiltrate around the bulb of the hair follicle.4 In rats with alopecia areata, tacrolimus is able to induce a drastic reduction in the follicular inflammatory infiltrate on the site of topical application.5 In addition, there was regrowth of hair in C3H7HeJ mice with alopecia areata treated with topical tacrolimus.6 Based on these data, topical tacrolimus might also be effective in humans with alopecia areata. To date, there are few data on this hypothesis.7 Therefore, we offered topical treatment with 0·1% tacrolimus ointment (Protopic®) to patients with long‐standing alopecia areata.