Autophagy influences adaptive immunity by routing intracellular material into the MHC class II antigen presentation pathway, enabling CD4 positive T cells to monitor cytosolic and nuclear proteins normally hidden from endosomal processing. Foundational work by Yoshinori Ohsumi at Tokyo Institute of Technology defined the core autophagy machinery that makes this routing possible, and subsequent immunology studies clarified how those processes intersect with antigen loading.
Mechanisms linking autophagy and MHC class II
Macroautophagy sequesters portions of cytosol, organelles, and protein aggregates into double-membrane autophagosomes that fuse with late endosomes and lysosomes where MHC class II loading occurs. Christian Münz at University of Zurich demonstrated that autophagy-dependent delivery of viral and self antigens to MHC class II compartments enhances presentation to CD4 positive T cells. Chaperone-mediated autophagy and selective autophagy receptors can also target specific proteins for lysosomal entry, a process highlighted by Ana Maria Cuervo at Albert Einstein College of Medicine who has characterized selective trafficking of cytosolic cargo into lysosomes. These routes expand the peptide repertoire available for class II presentation beyond endocytosed extracellular antigens.
Relevance, causes, and consequences
Autophagy-modulated presentation matters for infection control, tolerance, and immunopathology. Vojo Deretic at University of New Mexico reported that autophagy helps present bacterial and viral antigens, shaping helper T cell responses important in control of intracellular pathogens such as Mycobacterium tuberculosis, which is highly relevant in regions with elevated tuberculosis burden and shapes local public health priorities. Conversely, increased autophagic delivery of self proteins to MHC class II compartments can raise the visibility of self antigens to autoreactive CD4 positive T cells, contributing to autoimmunity in genetically susceptible individuals. The net effect is context-dependent and varies with cell type, antigen source, and inflammatory milieu.
Clinically, manipulating autophagy is being explored to improve vaccine antigen presentation and to enhance tumor antigen display to helper T cells, thereby supporting cytotoxic responses. At the same time, altering autophagy has systemic consequences for metabolism, infection susceptibility, and tissue homeostasis, so therapeutic targeting requires precise understanding of cell-specific roles. Ongoing translational research aims to exploit autophagy’s dual role in antigen routing and cellular quality control to balance protective immunity with prevention of immune-mediated damage.