Butyrophilin-Like 2 (BTNL2) Controls Auto-Aggressive Dermal Gamma Delta T Lymphocytes That Attack Human Hair Follicles

This study investigates the role of Butyrophilin-like 2 (BTNL2) in regulating gamma delta T cells (γδ TCs) in the context of alopecia areata (AA), an autoimmune disease affecting hair follicles (HFs). The researchers found that BTNL2 expression in the scalp HF epithelium reduces NKG2D expression and IFNγ production by skin Vδ1+γδ TCs, which are involved in the immune response. BTNL2 was primarily expressed by outer root sheath keratinocytes in healthy HFs, but its expression decreased in stressed HFs, which showed increased cytotoxic activity and signs of AA. The study suggests that BTNL2 is a key factor in AA pathobiology and could be a target for therapeutic strategies aimed at upregulating BTNL2 to protect HF immune privilege.