Peptide loading onto recycling HLA-DR molecules occurs in early endosomes

✍ Scribed by Valérie M. Pinet; Eric O. Long

• Book ID: 101315089
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 125 KB
• Volume: 28
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/(sici)1521-4141(199803)28:03<799::aid-immu799>3.0.co;2-5

✦ Synopsis

Presentation of exogenous antigens to MHC class II-restricted T cells can follow two different processing pathways. The classical pathway requires newly synthesized MHC class II molecules, invariant chain and HLA-DM expression, whereas the alternative pathway is independent of protein synthesis, invariant chain and HLA-DM. In both cases, MHC class II molecules associate with peptides derived from exogenous antigens that have been processed in endocytic compartments. Different endosomal/prelysosomal compartments where peptide/MHC class II complexes and HLA-DM molecules accumulate have been described. We show here that the alternative pathway uses an earlier compartment than the classical pathway. Experiments with chemically cross-liniked antigen suggest that recycling MHC class II molecules present rapidly degraded antigens, leading to a rapid immune response to exogenously added influenza virus proteins.