The skin is the first-line barrier to protect the body from external injury, such as ultraviolet light, infections, trauma, etc. [36] In addition to resident immunocytes which maintain skin immunological homeostasis, keratinocytes themselves can act as immune sensors, and can modulate skin immune and inflammatory reactions through exciting cytokine and chemokine release, promoting immunological and major histocompatibility complex (MHC) molecule expressions, recruiting immune cells, and further promoting inflammatory and immune processes [36–42]. Here, HLA-C is linked to infection.