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Visualizing Antigen Specific CD4+ T Cells using MHC Class II Tetramers
15:42

Visualizing Antigen Specific CD4+ T Cells using MHC Class II Tetramers

Published on: March 6, 2009

Peptide-specific intercellular transfer of MHC class II to CD4+ T cells directly from the immunological synapse upon

Scott A Wetzel1, Timothy W McKeithan, David C Parker

  • 1Department of Molecular Microbiology and Immunology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.

Journal of Immunology (Baltimore, Md. : 1950)
|December 22, 2004
PubMed

The transfer of membrane proteins from APC to T cells was initially described in the 1970s, and subsequent work has described two mechanisms of transfer: APC-derived exosomes and direct transfer of small packets, while cells remain conjugated. Using fibroblast APC expressing a GFP-tagged I-E(k) molecule with covalently attached antigenic peptide, we observed a third mechanism in live cell imaging: T cells spontaneously dissociating from APC often capture MHC:peptide complexes directly from the immunological synapse. Using two I-E(k)-restricted murine TCR transgenic T cells with different peptide specificity, we show in this study that the MHC transfer is peptide specific. Using blocking Abs, we found that MHC:peptide transfer in this system requires direct TCR-MHC:peptide interactions and is augmented by costimulation through CD28-CD80 interactions. Capture of the GFP-tagged MHC:peptide complexes correlates with an activated phenotype of the T cell, elevated CD69 with down-modulated TCR. The transferred MHC:peptide molecules transferred to the T cell are associated with molecules that imply continued TCR signaling; p56(lck), phosphotyrosine, and polarization of the actin cytoskeleton.

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