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.
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.