Reprogrammed Foxp3+ Regulatory T Cells Provide Essential Help to Support Cross-presentation and CD8+ T Cell Priming in Naive Mice

132 Scopus citations

Abstract

Foxp3+ regulatory T (Treg) cells can undergo reprogramming into a phenotype expressing proinflammatory cytokines. However, the biologic significance of this conversion remains unclear. We show that large numbers of Treg cells undergo rapid reprogramming into activated T helper cells after vaccination with antigen plus Toll-like receptor 9 (TLR-9) ligand. Helper activity from converted Treg cells proved essential during initial priming of CD8+ T cells to a new cross-presented antigen. Help from Treg cells was dependent on CD40L, and (unlike help from conventional non-Treg CD4+ cells) did not require preactivation or prior exposure to antigen. In hosts with established tumors, Treg cell reprogramming was suppressed by tumor-induced indoleamine 2,3-dioxygenase (IDO) and vaccination failed because of lack of help. Treg cell reprogramming, vaccine efficacy, and antitumor CD8+ T cell responses were restored by pharmacologic inhibition of IDO. Reprogrammed Treg cells can thus participate as previously unrecognized drivers of certain early CD8+ T cell responses.

Original languageEnglish (US)
Pages (from-to)942-954
Number of pages13
JournalImmunity
Volume33
Issue number6
DOIs
Publication statusPublished - Dec 14 2010

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ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Infectious Diseases

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