HAIR FOLLICLE STRUCTURES TARGETED BY ANTIBODIES IN PATIENTS WITH ALOPECIA-AREATA

Objective: To identify the structures in hair follicles (HFs) targeted by alopecia areata (AA) antibodies and the role of antigen expression in the development or localization of AA lesions. Design: The identit y of HF structures targeted by AA antibodies was determined by indirec t immunofluorescence and the level of antigen expression from the inte nsity of the staining. Setting: A university medical center. Patients: Ten patients with active AA and 8 control individuals. Results: Antib odies to anagen HFs were present in up to 90% of patients with AA but in less than 37% of controls. The antibodies in patients with AA react ed to antigens present only in HFs. The structures most commonly targe ted were the outer root sheath and, less often, the inner root sheath, matrix, and hair shaft. The same HF structure contained several immun ologically distinct antigens reactive with AA antibodies. The expressi on of some AA antigens was much greater in the scalp of patients with AA than in normal individuals. Conclusions: These findings indicate th at the autoantibody responses to HFs in patients with AA are heterogen eous and target multiple structures in anagen HFs. The expression of s ome as-yet-unidentified HF antigens is increased in many patients with AA, suggesting that the initiation, localization, severity, and persi stence of the disease may be related to the level of expression of som e HF antigens.