Human leukocyte antigen gene complex (HLA complex)

The human leukocyte antigen gene complex (HLA complex) is a highly polymorphic genomic region on chromosome 6 that encodes cell-surface proteins essential for the adaptive immune system, particularly in presenting peptides to T cells and regulating immune recognition of self and non-self[2][3][9]. It includes three main subgroups: HLA class I genes (HLA-A, -B, -C), presenting intracellular peptides to CD8+ T cells and expressed on almost all nucleated cells; HLA class II genes (HLA-DP, -DQ, -DR), presenting extracellular peptides to CD4+ T helper cells and mainly expressed on antigen-presenting cells; and class III genes, encoding immune regulatory proteins such as complement and cytokines[1][2][3][8][9]. The extensive polymorphism in the complex enables broad recognition of pathogens but underlies difficulties in transplant compatibility and predisposes to various autoimmune diseases, infections, and adverse drug reactions. The HLA gene complex is a crucial therapeutic target in transplantation, autoimmune disease risk prediction, and pharmacogenetics, although it is rarely the direct target of drugs[5][7][8].

Other names

Human major histocompatibility complexMHC gene complexHLA system

Modulation of immune recognition and response through inhibition or masking of HLA-antigen presentation (e.g., transplant immunosuppression); Antibody-mediated neutralization or depletion of cells presenting specific HLA molecules