Antigen processing and intracellular traffic of antigens and MHC molecules.

Antigen processing leads to binding of antigenic peptides to major histocompatibility complex (MHC) molecules, and these peptide-MHC complexes are recognized by T cells. The class I and class II MHC antigen processing pathways employ different mechanisms and patterns of intracellular transport that allow the two classes to bind and present peptides from different subcellular compartments, determining the source and nature of peptides to be presented.