Format

Send to

Choose Destination
EMBO J. 2007 Oct 3;26(19):4263-72. Epub 2007 Sep 6.

T cell-induced secretion of MHC class II-peptide complexes on B cell exosomes.

Author information

1
Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.

Abstract

Antigen-specific interactions between B cells and T cells are essential for the generation of an efficient immune response. Since this requires peptide-MHC class II complexes (pMHC-II) on the B cell to interact with TCR on antigen-specific T cells, we have examined the mechanisms regulating the persistence, loss, and secretion of specific pMHC-II complexes on activated B cells. Using a mAb that recognizes specific pMHC-II, we found that activated B cells degrade approximately 50% of pMHC-II every day and release 12% of these pMHC-II from the cell on small membrane vesicles termed exosomes. These exosomes directly stimulate primed, but not naïve, CD4 T cells. Interestingly, engagement of antigen-loaded B cells with specific CD4 T cells stimulates exosome release in a manner that can be mimicked by pMHC-II crosslinking. Biochemical studies revealed that the pMHC-II released on exosomes was previously expressed on the plasma membrane of the B cells, suggesting that regulated exosome release from activated B cells is a mechanism to allow pMHC-II to escape intracellular degradation and decorate secondary lymphoid organs with membrane-associated pMHC-II complexes.

PMID:
17805347
PMCID:
PMC2230838
DOI:
10.1038/sj.emboj.7601842
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center