Human leukocyte antigen class II peptide complex (HLA-II-peptide complex)

Human leukocyte antigen (HLA) class II peptide complexes are cell-surface heterodimers composed of alpha and beta chains that present processed exogenous peptides to CD4+ T lymphocytes. While primarily expressed on professional antigen-presenting cells (APCs) such as dendritic cells, B cells, and macrophages, they are also frequently expressed on leukemic cells, including those in acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL) (PubMed: 28455390). These complexes play a pivotal role in the immune system by facilitating the recognition of foreign or abnormal proteins, thereby triggering an adaptive immune response (UniProt: P01903). In oncology, they serve as critical targets for T-cell receptor (TCR)-based therapies, where engineered T cells are designed to recognize specific tumor-associated peptides presented by HLA class II molecules (PubMed: 31611615). The high degree of polymorphism in HLA genes necessitates a personalized approach to therapy, often requiring matching of the patient's HLA type with the therapeutic agent. Challenges in targeting these complexes include the potential for off-target toxicity against healthy tissues and the complex dynamics of the tumor microenvironment that can lead to immune evasion.

Other names

MHC class II-peptide complexpMHCIIHLA-DR-peptide complexHLA-DQ-peptide complexHLA-DP-peptide complexHLA class II-antigen complex

Recognition by engineered T-cell receptors (TCRs) or monoclonal antibodies to trigger T-cell mediated cytotoxicity or modulate antigen presentation by binding to the specific peptide-HLA interface.