The comings and goings of MHC class I molecules herald a new dawn in cross-presentation Review uri icon


MeSH Major

  • CD8-Positive T-Lymphocytes
  • Cross-Priming
  • Dendritic Cells
  • Endoplasmic Reticulum
  • Infection
  • Phagosomes
  • Proteasome Endopeptidase Complex


  • MHC class I (MHC-I) molecules are the centerpieces of cross-presentation. They are loaded with peptides derived from exogenous sources and displayed on the plasma membrane to communicate with CD8 T cells, relaying a message of tolerance or attack. The study of cross-presentation has been focused on the relative contributions of the vacuolar versus cytosolic pathways of antigen processing and the location where MHC-I molecules are loaded. While vacuolar processing generates peptides loaded onto vacuolar MHC-I molecules, how and where exogenous peptides generated by the proteasome and transported by TAP meet MHC-I molecules for loading has been a matter of debate. The source and trafficking of MHC-I molecules in dendritic cells have largely been ignored under the expectation that these molecules came from the Endoplasmic reticulum (ER) or the plasma membrane. New studies reveal a concentrated pool of MHC-I molecules in the endocytic recycling compartment (ERC). These pools are rapidly mobilized to phagosomes carrying microbial antigens, and in a signal-dependent manner under the control of Toll-like receptors. The phagosome becomes a dynamic hub receiving traffic from multiple sources, the ER-Golgi intermediate compartment for delivering the peptide-loading machinery and the ERC for deploying MHC-I molecules that alert CD8 T cells of infection.

publication date

  • July 2016



  • Review



  • eng

PubMed Central ID

  • PMC4942502

Digital Object Identifier (DOI)

  • 10.1111/imr.12428

PubMed ID

  • 27319343

Additional Document Info

start page

  • 65

end page

  • 79


  • 272


  • 1