CD8A and viral infectious disease: CD103, a well-characterized marker for TRMs, is an integrin that binds E-cadherin which enables TRMs to remain permanently in the peripheral tissues without recirculating.25 CD103 is required for TRM formation, which enables superior protection against cutaneous viral infections.26 CD103+ TRMs in skin are enriched in the epidermis and are associated with potent effector cytokine production.14 In our study, an increased frequency of CD103+CD8 T cells was identified in cSCC tumors compared with normal skin.