Major Histocompatibility Complex (MHC) and Antigen-Presenting Cell Receptors (MHC/APC Receptors)

Antigen-presenting cell (APC) receptors and Major Histocompatibility Complex (MHC) class I and II molecules are fundamental components of the adaptive immune system, facilitating the recognition of antigens by T-cells (Rock et al., 2016, Nature Reviews Immunology). MHC class I molecules typically present endogenous peptides to CD8+ T-cells, while MHC class II molecules present exogenous peptides to CD4+ T-cells (Wieczorek et al., 2017, Frontiers in Immunology). Cross-presentation is a specialized pathway where exogenous antigens are processed and presented on MHC class I molecules, a process essential for generating cytotoxic T-cell responses against tumors and viruses (Joffre et al., 2012, Nature Reviews Immunology). This system is a primary target for cancer vaccines and adjuvants, such as TLR agonists, which aim to enhance the efficiency of antigen loading and APC activation (Embgenbroich & Burgdorf, 2018, Frontiers in Immunology). In clinical settings, the expression levels of MHC molecules and specific HLA genotypes are used as biomarkers to predict the efficacy of immunotherapies (Garrido et al., 2016, Cancer Immunology, Immunotherapy). However, therapeutic manipulation of these pathways carries risks, including the potential for inducing autoimmune reactions or cytokine release syndrome due to over-activation of the immune system (June et al., 2018, New England Journal of Medicine). The complexity of this system involves multiple intracellular transporters and chaperones, such as TAP and tapasin, which ensure proper peptide loading (Blum et al., 2013, Annual Review of Immunology). Dysregulation or downregulation of MHC molecules is a common mechanism of immune evasion used by various cancers to avoid detection by T-cells (Cornel et al., 2020, Frontiers in Oncology).

Other names

MHC-peptide complexAntigen-presenting cell machineryCross-presentation pathwayHLA-peptide complexAntigen processing and presentation machinery

Modulation of antigen processing and presentation pathways to enhance or suppress T-cell activation.