HLA-DR (L243) Mouse mAb (PE Conjugate) #78397

The human leukocyte antigen (HLA) system is a gene complex encoding the major histocompatibility complex (MHC) proteins in humans. These cell surface proteins are responsible for the regulation of antigen-specific immunity in humans. HLA genes are highly polymorphic, allowing them to fine-tune the adaptive immune response. HLAs corresponding to MHC class I (HLA-A, B, and C) present small peptide antigens from inside the cell, approximately 8 to 10 amino acids in length, to CD8⁺ T lymphocytes in order to activate a cytotoxic T cell response. HLAs corresponding to MHC class II (HLA-DP, DM, DO, DQ, and DR) present antigens from outside of the cell, approximately 15 to 24 residues in length, to CD4⁺ T helper cells, which in turn secrete cytokines and stimulate B cells to produce antibodies to that specific antigen. HLAs corresponding to MHC class III encode components of the complement system (1,2).

The L243 antibody reacts with a member of the human MHC Class II antigens, HLA-DR. The HLA-DR antigen is expressed on B lymphocytes, activated T lymphocytes, activated NK cells, monocytes, macrophages, other antigen presenting cells, and progenitor cells (3).