Background: Tacrolimus (FK 506), a metabolite of the fungus Streptomyces tsukubaensis, is an anti-T-cell drug. It acts by inhibiting the production of IL-2, IL-3, IL-4, TNFα, and GM-CSF. More potent and with slightly less secondary effects than cyclosporine, it has been the object of considerable interest, especially in conditions that could benefit from the latter. Objective: In psoriasis, a placebo-controlled double-blind study has shown oral tacrolimus at 0.1 mg/kg/day to be effective in controlling recalcitrant lesions. In human, small studies have reported tacrolimus ointment to be effective in controlling acute contact dermatitis. Short-term trials of topical tacrolimus in the treatment of atopic dermatitis have recently shown excellent results in both adults and children. In animal studies of hair growth disorders, topical tacrolimus induces anagen and protects from chemotherapy-induced alopecia. Animal studies with the ointment for the prevention of skin graft rejection, lupus dermatoses, and skin papilloma formation have also shown to be promising. Conclusions: There are case reports of pyoderma gangrenosum, Sezary's syndrome, and Behçet's disease successfully treated with oral tacrolimus but, because of their small number, they remain anecdotal at this point.
FK-506 related compounds produced by Streptomyces tsukubaensis No.9993.