Human leukocyte antigen class I histocompatibility antigen (HLA class I)

Human leukocyte antigen class I histocompatibility antigen (HLA class I) is a cell surface glycoprotein complex found on all nucleated cells and is essential for the presentation of endogenous antigenic peptides to cytotoxic (CD8+) T lymphocytes[1][4][5][6]. Composed of a polymorphic heavy chain (α chain) encoded within the HLA region on chromosome 6 and a nonpolymorphic beta-2 microglobulin light chain, HLA class I forms a peptide-binding groove that presents 8–10 amino acid peptides derived from intracellular proteins[1][5][6]. This antigen presentation process is crucial for immune surveillance, enabling the detection and elimination of infected or malignant cells by cytotoxic T cells[1][4][6]. Multiple HLA class I genes (such as HLA-A, HLA-B, HLA-C) encode distinct proteins, contributing to genetic diversity and immune function[6]. Loss or alteration of class I HLA expression is associated with cancer immune evasion and plays a central role in organ transplant compatibility and autoimmune disease susceptibility[6]. The HLA class I complex is a prominent therapeutic target in immuno-oncology, transplantation medicine, and autoimmune disease research[6][5][1].

Other names

HLA class I moleculeMajor histocompatibility complex class I (MHC class I)HLA-A, HLA-B, HLA-C (specific gene products)HLA-I

Modulate antigen presentation to T cells; Alter immune cell recognition and targeting of infected or malignant cells; Modulate immune checkpoint activity (by facilitating or impairing presentation to cytotoxic T cells)