What evidence supports the hypothesis of an autoimmune pathophysiology for alopecia areata?

Updated: Aug 06, 2020
  • Author: Chantal Bolduc, MD, FRCPC; Chief Editor: Dirk M Elston, MD  more...
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Studies in humans also reinforce the hypothesis of autoimmunity. Studies have shown that hair regrows when affected scalp is transplanted onto SCID (severe combined immunodeficiency) mice that are devoid of immune cells. Autologous T lymphocytes isolated from an affected scalp were cultured with hair follicle homogenates and autologous antigen-presenting cells. Following initial regrowth, injection of the T lymphocytes into the grafts resulted in loss of regrown hairs. Injections of autologous T lymphocytes that were not cultured with follicle homogenates did not trigger hair loss.

A similar experiment on nude (congenitally athymic) mice failed to trigger hair loss in regrown patches of alopecia areata after serum from affected patients was injected intravenously into the mice. However, the same study showed that mice injected with alopecia areata serum showed an increased deposition of immunoglobulin and complement in hair follicles of both grafted and nongrafted skin compared with mice injected with control serum, which showed no deposition.

In addition, research has shown that alopecia areata can be induced using transfer of grafts from alopecia areata–affected mice onto normal mice. Transfer of grafts from normal mice to alopecia areata–affected mice similarly resulted in hair loss in the grafts.

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