Indirect activation of naïve CD4+ T cells by dendritic cell–derived exosomes

✍ Scribed by Théry, Clotilde; Duban, Livine; Segura, Elodie; Véron, Philippe; Lantz, Olivier; Amigorena, Sebastian

• Book ID: 109923541
• Publisher: Nature Publishing Group
• Year: 2002
• Tongue: English
• Weight: 381 KB
• Volume: 3
• Category: Article
• ISSN: 1529-2908
• DOI: 10.1038/ni854

✦ Synopsis

Dendritic cells (DCs) secrete vesicles of endosomal origin, called exosomes, that bear major histocompatibility complex (MHC) and T cell costimulatory molecules. Here, we found that injection of antigen- or peptide-bearing exosomes induced antigen-specific naïve CD4+ T cell activation in vivo. In vitro, exosomes did not induce antigen-dependent T cell stimulation unless mature CD8alpha- DCs were also present in the cultures. These mature DCs could be MHC class II-negative, but had to bear CD80 and CD86. Therefore, in addition to carrying antigen, exosomes promote the exchange of functional peptide-MHC complexes between DCs. Such a mechanism may increase the number of DCs bearing a particular peptide, thus amplifying the initiation of primary adaptive immune responses.