NKG2A/CD94 is an inhibitory receptor binding HLA-E and expressed on tumor infiltrating cytotoxic NK and CD8+ T cells. Cancer cells can protect themselves from killing by NKG2A+ lymphocytes via expressing HLA-E. The up-regulation of HLA-E is observed on many types of solid tumors and hematological malignancies. In some types of tumors, high expression level of HLA-E is related to poorer prognosis.
NKG2A is a receptor for HLA-E, which is expressed on a wide variety of viral, inflammatory and malignant cells. By expressing HLA-E, abnormal cells can escape from destruction by NGK2A+ immune cells. When NKG2A/HLA-E inhibitors block the inhibitory function of NKG2A receptors on immune cells such as NK and CD8+ T cells, they can restore the killing activity of these immune cells. It should be noted that NKG2A/HLA-E inhibitors can simultaneously activate NK and T cells, leading to more effective immune response.