Hair follicle structures targeted by antibodies in patients with alopecia areata
D. J. Tobin, S. K. Hann, M. S. Song and J. C. Bystryn
Department of Dermatology, New York University Medical Center, New York, USA.
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 identity of HF
structures targeted by AA antibodies was determined by indirect
immunofluorescence and the level of antigen expression from the intensity
of the staining. SETTING: A university medical center. PATIENTS: Ten
patients with active AA and 8 control individuals. RESULTS: Antibodies 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 reacted to antigens
present only in HFs. The structures most commonly targeted were the outer
root sheath and, less often, the inner root sheath, matrix, and hair shaft.
The same HF structure contained several immunologically distinct antigens
reactive with AA antibodies. The expression of some AA antigens was much
greater in the scalp of patients with AA than in normal individuals.
CONCLUSIONS: These findings indicate that the autoantibody responses to HFs
in patients with AA are heterogeneous and target multiple structures in
anagen HFs. The expression of some as-yet-unidentified HF antigens is
increased in many patients with AA, suggesting that the initiation,
localization, severity, and persistence of the disease may be related to
the level of expression of some HF antigens.
