HLA-Dra

Human leukocyte antigen-DRA (HLA-DRA) gene is a crucial gene of DR subtype of MHC Ⅱ. The α chain encoded by it can form HLA-DR heterodimer by non-covalent bond with β chain. The dimer mainly exists in antigen presenting cells and presents exogenous antigens to helper T cells (Th) to initiate immune response. Some research suggested that HLA-DRA can be expressed in lung cancer, gastric cancer, colorectal cancer, kidney cancer, breast cancer, ovarian cancer, cervical cancer and other tumors, and the mainstream believes that its high expression is a good prognostic factor for patients, which is because HLA-DRA can enhance the antitumor immune activity of cytotoxic T cells (CTL) by recruiting Th and promoting the secretion of IFN-γ and TNF-α, and its down-regulation will lead to the loss of tumor immune monitoring. However, HLA-DRA positivity in HBV related hepatocellular carcinoma is associated with tumor development, speculated that virus infected HLA-DR+ cancer cells can induce CTL depletion and form an inhibitory microenvironment synergistically with PD-L1.