Alopecia areata: infiltration of Th17 cells in the dermis, particularly around hair follicles.

BACKGROUND

The precise pathogenesis of alopecia areata remains unknown, although this disease seems to be triggered by helper T cell infiltration in hair follicles. Recent studies of psoriasis and vitiligo have demonstrated the involvement of Th17 cells. Psoriasis and vitiligo occasionally develop concomitantly or inversely in patients with alopecia areata.

OBJECTIVE

The aim of this study was to determine whether Th17 cells are present in the affected lesions of alopecia areata.

METHODS

We performed immunofluorescent staining of representative immunocompetent cells that had infiltrated into the skin of the scalp in 4 individuals with alopecia areata (single patchy alopecia areata, multiple patchy alopecia areata, alopecia totalis and alopecia universalis).

RESULTS

We found the infiltration of CD4(+)IL-17A(+) Th17 cells in the dermis, particularly around hair follicles, in all 4 cases.

CONCLUSIONS

These findings suggest the possibility that alopecia areata is induced by a Th17 cell-associated autoimmune mechanism.