Does collapse of immune privilege in the hair-follicle bulge play a role in the pathogenesis of primary cicatricial alopecia?

The study investigated the potential role of immune privilege (IP) collapse in the hair-follicle bulge in the pathogenesis of primary cicatricial alopecia (PCA), a group of inflammatory disorders leading to permanent hair loss. The research involved three patients with distinct PCA variants, examining paired biopsies from affected and unaffected scalp areas. Immunohistochemical analysis revealed increased expression of major histocompatibility complex (MHC) classes I and II and beta2-microglobulin in the bulge region of affected follicles, alongside reduced expression of the bulge marker keratin 15 in two cases. These findings suggested that the collapse of IP in the bulge region might contribute to PCA pathogenesis by allowing immune-mediated damage to epithelial hair-follicle stem cells, leading to permanent follicle loss.