Major histocompatibility complex antigen presentation machinery (MHC antigen presentation machinery)

The major histocompatibility complex (MHC) antigen presentation machinery encompasses a set of molecules and associated pathways in host cells that process protein antigens (from intracellular or extracellular sources) and present them as peptides, bound to MHC class I or II molecules, on the cell surface for recognition by T cells. For MHC class I, endogenous antigens are degraded by the proteasome, transported via TAP into the endoplasmic reticulum, assembled with newly synthesized MHC molecules, and displayed for recognition by cytotoxic CD8^+ T cells[1][2][4][5][7][9]. For MHC class II, exogenous antigens are processed in endosomes, loaded onto MHC-II molecules facilitated by chaperones like CD74 and HLA-DM, and presented to helper CD4^+ T cells[6]. This machinery forms the centerpiece of immunosurveillance, is crucial for anti-tumor and antiviral responses, and is subject to evasion or manipulation by pathogens and cancer cells for survival[1][6][7][8][9][10].

Other names

Antigen processing and presentation machineryMHC antigen presentation pathwayantigen presentation pathwayAPM

Restoration or modulation of antigen presentation (immune checkpoint inhibition, upregulation of MHC or associated molecules); Inhibition of antigen processing (proteasome inhibitors can reduce peptide supply for MHC loading); Preventing immune evasion by disrupting viral or tumor interference mechanisms