Epidermal γδ T Cells, CD8 T Cells, and Macrophages Are Increased in Number in Alopecia Areata and Express BST2 as Part of an Interferon-Driven Antiviral Gene Signature

This study investigates the role of various immune cells in alopecia areata, an autoimmune disorder causing hair loss. The research highlights the involvement of epidermal γδ T cells and macrophages, alongside the known role of CD8 T cells, in the disease's pathogenesis. Using single-cell RNA sequencing data from mice, the study shows that these cells express BST2, an interferon-stimulated antiviral protein, which is elevated in alopecia areata and decreases with JAK inhibitor treatment. The findings suggest that BST2 is a marker of immune activation in alopecia areata, emphasizing the contribution of epidermal γδ T cells to the condition.