Antigen Presentation Machinery (APM)

The Antigen Presentation Machinery (APM) is a coordinated cellular system responsible for the processing of intracellular and extracellular proteins into peptides and their subsequent display on Major Histocompatibility Complex (MHC) molecules at the cell surface (nih.gov, 1.2.1). This machinery is fundamental to adaptive immunity, as it allows CD8+ and CD4+ T cells to survey the proteome for signs of infection or malignant transformation (oup.com, 1.2.3). Key components include the immunoproteasome for peptide generation, the Transporter associated with Antigen Processing (TAP) for peptide translocation, and the peptide-loading complex (including tapasin and calreticulin) for assembly with MHC molecules (mdpi.com, 1.3.3). In many cancers, the APM is frequently downregulated or mutated to evade immune detection, which contributes to resistance against immune checkpoint inhibitors (nih.gov, 1.1.1). Therapeutic strategies targeting the APM aim to restore or enhance its function through epigenetic modulators like HDAC inhibitors, cytokines such as interferons, or targeted small molecules to increase tumor immunogenicity (bmj.com, 1.4.2). Enhancing APM activity is a major strategy to improve the efficacy of T cell-based immunotherapies and overcome immune escape in solid tumors (mdpi.com, 1.1.4).

Other names

Antigen Processing and Presentation MachineryAPP MachineryMHC Class I Presentation PathwayHLA Class I Antigen Presentation MachineryMHC Class II Presentation Pathway

Upregulation of MHC class I and II expression, epigenetic restoration of antigen processing genes, enhancement of peptide loading and transport, and modulation of proteasomal degradation to alter the immunopeptidome.