Major histocompatibility complex class II antigen presentation pathway (MHC class II antigen presentation)

The MHC class II antigen presentation pathway is a central process in the adaptive immune response, in which specialized antigen-presenting cells such as dendritic cells, macrophages, and B cells internalize exogenous antigens (from pathogens or the environment), process these proteins into peptides, and load the resulting fragments onto MHC class II molecules. These peptide-MHC class II complexes are then displayed on the cell surface, where they are recognized by CD4\(^+\) T cells, triggering their activation and differentiation. This pathway is fundamental for the initiation of immune responses against extracellular pathogens and for the regulation of immune tolerance, and its dysfunction is associated with autoimmune disease, infection, and cancer. If you need structured details for a molecule rather than a pathway, specify the particular MHC class II molecule (such as "HLA-DR" or "HLA-DQ").

Other names

MHC class II pathwayHLA class II pathway (human-specific)Antigen presentation to CD4\(^+\) T cellsMHC-II-mediated antigen presentation

Inhibition of proteases (e.g., cathepsin S inhibitors prevent peptide loading onto MHC class II molecules); Broad immunosuppression (reduced antigen presentation by APCs); Blockade of co-stimulatory signals, preventing T cell activation