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Author Notes:

Correspondence: John D. Altman; Email: jaltman@emory.edu

Authors' Contributions: Conceived and designed the experiments: PAR and JDA.

Performed the experiments: PAR, MFP and GDL.

Analyzed the data: PAR and JDA.

Wrote the paper: PAR and JDA.

Acknowledgments: Thanks to Rafi Ahmed and Barry Rouse for critical comments on the manuscript.

Disclosures: The authors have declared that no competing interests exist.


Research Funding:

Support for this research came from National Institutes of Health (USA), grant 1RO1AI042373, and the Emory Vaccine Center Flow Cytometry Core Facility, Emory Center for AIDS Research (P30 AI050409).

CD8 T Cell Memory Recall Is Enhanced by Novel Direct Interactions with CD4 T Cells Enabled by MHC Class II Transferred from APCs

Journal Title:



Volume 8, Number 2


, Pages 1-10

Type of Work:

Article | Final Publisher PDF


Protection against many intracellular pathogens is provided by CD8 T cells, which are thought to need CD4 T cell help to develop into effective memory CD8 T cells. Because murine CD8 T cells do not transcribe MHC class II (MHC-II) genes, several models have proposed antigen presenting cells (APCs) as intermediaries required for CD4 T cells to deliver their help to CD8 T cells. Here, we demonstrate the presence of MHC-II molecules on activated murine CD8 T cells in vitro as well as in vivo. These MHC-II molecules are acquired via trogocytosis by CD8 T cells from their activating APCs, particularly CD11c positive dendritic cells (DCs). Transferred MHC-II molecules on activated murine CD8 T cells were functionally competent in stimulating specific indicator CD4 T cells. CD8 T cells that were “helped” in vitro and subsequently allowed to rest in vivo showed enhanced recall responses upon challenge compared to “helpless” CD8 T cells; in contrast, no differences were seen upon immediate challenge. These data indicate that direct CD8[ratio]CD4 T cell interactions may significantly contribute to help for CD8 T cells. Furthermore, this mechanism may enable CD8 T cells to communicate with different subsets of interacting CD4 T cells that could modulate immune responses.

Copyright information:

© 2013 Romagnoli et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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