Alopecia areata is a T-lymphocyte mediated autoimmune disease: Lesional human T-lymphocytes transfer alopecia areata to human skin grafts on SCID mice

Much evidence suggests that alopecia areata is a tissue restricted autoimmu ne disease. Alopecia areata responds to immunosuppressive agents, and is as sociated with other tissue restricted autoimmune diseases, including autoim mune thyroiditis and vitiligo. Furthermore, hair regrows when involved scal p is transplanted to nude mice. This study was undertaken to determine whet her alopecia areata is mediated by T lymphocytes, Involved scalp from alope cia areata patients was grafted onto SCID mice. Additional biopsies from le sional scalp of the same patients were used to isolate T lymphocytes. These T lymphocytes were cultured with hair follicle homogenate, as well as auto logous antigen presenting cells. The T lymphocytes were then injected into autologous scalp grafts on the then injected into SCID mice, which had regr own hair. Injection of scalp T lymphocytes resulted in hair loss. Hair loss was associated with the histologic and immunochemical changes of alopecia areata, including perifollicular infiltrates of T cells, along with HLA-DR and ICAM-1 expression by the follicular epithelium. Scalp T lymphocytes tha t had not been cultured with hair follicle homogenate did not have this eff ect. Preliminary data suggests hair loss requires collaboration between CD8 (+) and CD4(+)T cells. These studies have demonstrated that alopecia areata can be induced by the transfer of T cells that recognize a hair follicle a utoantigen.