Immunology of Alopecia Areata

Alopecia areata, a condition leading to hair loss, is largely considered an autoimmune disease, characterized by the collapse of the immune privilege of hair follicles. The condition has a higher incidence in females and is often associated with other autoimmune disorders, supporting the autoimmune hypothesis. Antibodies in alopecia areata typically attack hair follicles during the anagen phase, which is when melanogenesis occurs, indicating that melanogenesis-associated autoantigens might be involved. However, some researchers argue that alopecia areata may not be a true autoimmune disease, as no specific target autoantigen has been conclusively identified, and similar autoantibodies can be found in healthy individuals. The disease's high familial occurrence, with up to 42% of patients reporting a positive family history, suggests a significant genetic component. Despite these insights, the exact pathobiology of alopecia areata remains unclear.