The pro-inflammatory cytokine INF-γ was a robust up-regulator of MHC-I in vivo in anagen hair bulbs from murine back skin,[27] and was involved in immune-mediated damage to epithelial HFSCs.[28] In addition, the higher level of MHC-I expression may facilitate the autoimmune attack on HFs by CD8+ T cells.[29] In our study, GSEA of 4 hub IRGs all reveal that the INF-γ response pathway was the key pathway, and central memory CD8+ T cell and activated CD8+ T cell were significant increase in the bald group of male AGA. This evidence concerns the gene CD8A and Hand-foot syndrome.