Major histocompatibility complex (MHC) class I and class II molecules (MHC/HLA)

Major histocompatibility complex (MHC) class I and class II molecules, referred to as Human Leukocyte Antigens (HLA) in humans, are cell surface glycoproteins essential for the adaptive immune system's ability to recognize foreign antigens (StatPearls, 2023). MHC class I molecules are found on nearly all nucleated cells and present endogenous peptides to CD8+ cytotoxic T cells, while MHC class II molecules are primarily expressed on professional antigen-presenting cells and present exogenous peptides to CD4+ helper T cells (NIH, 2022). These molecules play a critical role in distinguishing self from non-self, which is fundamental for defense against pathogens and the elimination of transformed tumor cells (UniProt, 2024). In clinical practice, MHC molecules are the primary targets for managing organ transplant compatibility and preventing graft-versus-host disease (PubMed, 2021). Pharmacological intervention often involves immunosuppressive drugs like calcineurin inhibitors that block the signaling cascade initiated by MHC-TCR binding, or biologics that interfere with co-stimulatory signals (Nature Reviews Immunology, 2022). Additionally, specific HLA genotypes are used as biomarkers for autoimmune disease susceptibility and to predict severe adverse drug reactions, such as those associated with abacavir or carbamazepine (Wikipedia, 2024). Emerging therapies also include TCR-mimetic antibodies and personalized vaccines that specifically target the MHC-peptide complex to treat various cancers (PubMed, 2021).

Other names

Human leukocyte antigenHLAMHCTransplantation antigensMHC-IMHC-II

Modulation of the immune response by interfering with the presentation of antigens to T-cell receptors or by inhibiting the downstream signaling pathways initiated by MHC-TCR binding (StatPearls, 2023).