Major Histocompatibility Complex class I and II molecules (MHC I and II)

Major Histocompatibility Complex (MHC) class I and II molecules are essential cell surface glycoproteins that play a central role in the adaptive immune system by presenting processed peptide antigens to T-cells. MHC class I molecules are expressed on nearly all nucleated cells and present endogenous antigens to CD8+ cytotoxic T-cells, whereas MHC class II molecules are primarily found on professional antigen-presenting cells (APCs) like dendritic cells, macrophages, and B-cells, presenting exogenous antigens to CD4+ helper T-cells (Janeway et al., 2001, Immunobiology; StatPearls, 2023). This presentation is critical for the recognition of pathogens and malignant cells, as well as for maintaining self-tolerance. In clinical practice, MHC molecules are primary targets for managing transplant rejection and autoimmune disorders, where drugs like glatiramer acetate compete for MHC binding sites to shift the immune response (PubChem, 2024). Furthermore, MHC expression is often downregulated by tumors to evade immune detection, making the restoration or targeting of these molecules a key strategy in cancer immunotherapy. Understanding the polymorphic nature of MHC (HLA in humans) is also vital for personalized medicine, as specific HLA alleles are linked to drug hypersensitivities and disease susceptibility (NIH, 2023).

Other names

Human Leukocyte AntigenHLAMHC moleculesAntigen-presenting moleculesMajor Histocompatibility Complex

Modulation of antigen presentation, competitive binding to MHC grooves to prevent T-cell activation, and inhibition of T-cell receptor (TCR) signaling through interference with the MHC-peptide-TCR complex.