Hla-dr

HLA-DR

HLA-DR is a MHC class II cell surface receptor encoded by the human leukocyte antigen complex on chromosome 6 region 6p21.31. The complex of HLA-DR and its ligand, a peptide of 9 amino acids in length or longer, constitutes a ligand for the T-cell receptor (TCR). HLA (human leukocyte antigens) were originally defined as cell surface antigens that mediate graft-versus-host disease, which resulted in the rejection of tissue transplants in HLA-mismatched donors. Identification of these antigens has led to greater success and longevity in organ transplant.