CD8A and neoplasm: Actually, IL-27 has been demonstrated to stimulate PD-L1 expression in several cell types, including CD4+ and CD8+ T cells, monocytes, DC, and tumor cells [138,139,140] Therefore, IL-27 might cause possible actions regulating the expression in MMECs of HLA-I, which downregulates NK cell activity, and also that of PD-L2, which regulates the level of both CD8+ T and NK cell activity.