Fig. 1

Schematic diagram of the interplay between the autophagy-lysosomal and endo-/exosomal pathways and autophagy-associated antigen presentation. (A) The selective degradation of damaged or toxic material, including proteins, by the autophagy-lysosomal or endo-/exosomal pathways are coordinated processes that participate in protein homeostasis and contribute to antigen processing for MHC presentation. The two pathways converge with many common components, especially those that are involved in amphisome formation and the LAP process. Autophagy can regulate endosomal secretion to form extracellular vesicles, which can also regulate autophagy in a paracrine manner. (B) Autophagy is a novel pathway for endogenous and exogenous antigen presentation. Autophagosomes recruit cytosolic antigens to endosomal MHC loading compartments via lysosomal degradation and then present peptide-MHC to CD4⁺ or CD8⁺ T cells with the assistance of the costimulatory molecules. Abbreviations: APCs antigen presenting cells, ER endoplasmic reticulum, MHC major histocompatibility complex, LAP LC3-associated phagocytosis, MVB multivesicular bodies, PAS phagophore assembly site