title: Immunohistochemical characterization of the cellular infiltrate in severe alopecia areata before and after minoxidil treatment.
abstract: The mechanism of minoxidil-induced hair regrowth in alopecia areata (AA) is unknown. In vitro studies suggest that pharmacologic tissue levels of minoxidil may have both epithelial and T cell effects. Response in 36 of 47 patients with severe AA to topical minoxidil 5% b.i.d. was characterized by a return toward normal of hair follicle diameter, depth and structure, and an apparent shift in T cell populations from the skin into the peripheral blood. Nonresponders showed none of these changes. Biopsies from 34 patients subsequently treated with oral minoxidil 5 mg q. 12 h showed no further changes in perifollicular total T, helper-inducer T or suppressor-cytotoxic T cell counts; they did, however, demonstrate significant decreases in perifollicular Langerhans cell and activated T cell counts, and nearly significant decreases in perifollicular monocyte counts. It is possible that minoxidil may be altering a presumed follicular chemoattractive stimulus to a variety of cell types. Decreases in activated T cell counts suggest the possibility of direct immunomodulatory effects of minoxidil on T cells which might contribute to a hair regrowth response in AA.
mesh_terms: D000293:Adolescent; D000328:Adult; D000506:Alopecia Areata / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007801:Langerhans Cells / Q000187:drug effects; D007958:Leukocyte Count / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D008914:Minoxidil / Q000627:therapeutic use*; D009000:Monocytes / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects; D006377:T-Lymphocytes, Helper-Inducer / Q000187:drug effects
chemical_list: D008914:Minoxidil