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.

Medical treatments for male and female pattern hair loss

“…34 One study indicated that minoxidil responders had reduced T-cell infiltration compared with nonresponders. 58 Subsequent studies have shown no significant change in peribulbar or perivascular inflammation. 59,60 Therefore, it is unclear exactly whether or not minoxidil has immunosuppressive effects.…”

Alopecia Areata: Clinical Perspective and an Insight into Pathogenesis

“…During the acute phase of hair loss, degeneration of the tower follicular keratinocytes and matrix cells as well as of melanocytes, Langerhans cells and dermal papillae cells (24, 25) with a formation of dysplastic hair shaft is noted with a decreased anagen to telogen ratio, resulting in a marked increase in telogen and catagen hairs that may be observed in horizontal sections of the scalp skin. The areas of normal scalp (25) of patients with alopecia may also show dense peribulbar accumulations of initiating mononuclear cells, although the CD4/CD8 ratio may differ from that in active disease (26). The clinically normal scalp of affected patients can also show changes in the dermal papillae and at the dermo‐epidermal junction of the hair bulb similar to those in areas of active disease (25).…”

Treatment-Resistant Alopecia Areata

“…Biopsy specimens obtained from 34 patients subsequently treated with oral minoxidil (5 mg every 12 hours) demonstrated additional signifi¬ cant decreases in perifollicular Langerhans cell and activated T-cell counts and nearly significant de¬ creases in perifollicular monocyte counts. 12 These data suggest that in alopecia areata minoxidil may not only be stimulating the follicle to assume a more normal size and architecture, but that it also may be altering a presumed follicular chemoattractive stim¬ ulus or cell surface binding molecule.…”

“…Cosmetic response was maintained in 4 (80%) of 5 patients who continued treatment for as long as 84 weeks. All responders had evidence of hair regrowth by week 12. The rapidity and extent of hair regrowth were greater with combination therapy than with either drug used as a single agent.…”