Mobilizing monocytes to cross-present circulating viral antigen in chronic infection
Adam J. Gehring, … , Florent Ginhoux, Antonio Bertoletti
Adam J. Gehring, … , Florent Ginhoux, Antonio Bertoletti
Published August 1, 2013
Citation Information: J Clin Invest. 2013;123(9):3766-3776. https://doi.org/10.1172/JCI66043.
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Research Article Immunology

Mobilizing monocytes to cross-present circulating viral antigen in chronic infection

Abstract

Selection of antigens for therapeutic vaccination against chronic viral infections is complicated by pathogen genetic variations. We tested whether antigens present during persistent viral infections could provide a personalized antigenic reservoir for therapeutic T cell expansion in humans. We focused our study on the HBV surface antigen (HBsAg), which is present in microgram quantities in the serum of chronic HBV patients. We demonstrated by quantitative fluorescent microscopy that, out of 6 professional APC populations in the circulation, only CD14 monocytes (MNs) retained an HBsAg depot. Using TCR-redirected CD8+ T cells specific for MHC-I–restricted HBV epitopes, we showed that, despite being constantly exposed to antigen, ex vivo–isolated APCs did not constitutively activate HBV-specific CD8+ T cells. However, differentiation of HBsAg+ CD14 MNs from chronic patients to MN-derived DCs (moDCs) induced cross-presentation of the intracellular reservoir of viral antigen. We exploited this mechanism to cross-present circulating viral antigen and showed that moDCs from chronically infected patients stimulated expansion of autologous HBV-specific T cells. Thus, these data demonstrate that circulating viral antigen produced during chronic infection can serve as a personalized antigenic reservoir to activate virus-specific T cells.

Authors

Adam J. Gehring, Muzlifah Haniffa, Patrick T. Kennedy, Zi Zong Ho, Carolina Boni, Amanda Shin, Nasirah Banu, Adeline Chia, Seng Gee Lim, Carlo Ferrari, Florent Ginhoux, Antonio Bertoletti

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Figure 7

Expansion of autologous T cells by moDCs presenting in vivo–captured antigen.

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Expansion of autologous T cells by moDCs presenting in vivo–captured ant...
(A) IFN-γ ELISPOT for chronic HBV patient virus-specific T cells expanded with pools of synthetic peptides covering HBcAg (1 pool = core, 42 peptides) and HBsAg (2 pools = Env1 and Env2; 42 peptides each). Data displayed as fold above background to normalize variation among patients due to varying background for each assay. Positive cutoff was greater than 10 spots and 2 times the background. (B) IFN-γ ELISPOT for chronic patient virus-specific T cells after expansion with moDCs made using GM-CSF + IL-4. (C) IFN-γ ELISPOT for chronic patient virus-specific T cells after expansion with moDCs made using GM-CSF + IL-15. Positive responses for moDCs were defined as greater than 2 times the average of unstimulated wells and 10 or more spots. Background and responses for the moDC assays were lower than in peptide-expanded cultures and thus are presented as IFN-γ spots/105 cells. Intracellular cytokine staining to confirm (D) CD8+ and (E) CD4+ HBV-specific T cell expansion with moDCs presenting in vivo captured antigen. Cytokine staining shows responses from 2 separate patients and is representative of 4 patients where responses could be detected by intracellular staining. *Positive response; nt, not tested.