HLA class II histocompatibility antigen DR alpha chain

The HLA class II histocompatibility antigen, DR alpha chain (HLA-DRA) is a protein that forms the alpha subunit of the HLA-DR molecule, a major histocompatibility complex (MHC) class II protein. It plays a central role in adaptive immunity by presenting peptides derived from extracellular proteins to CD4-positive T cells via antigen-presenting cells (APCs). Unlike other MHC class II molecules, the DR alpha chain is practically invariant across individuals. It is expressed primarily on professional antigen-presenting cells and is crucial for immune surveillance against infections and tumors. It serves as a biomarker for cancer immunotherapy, specifically predicting therapeutic response to anti-PD-1 immunotherapy in NSCLC.

Presents extracellular-derived peptides to CD4+ T-cells for immune response modulation.