title: Human tumor antigen-specific helper and regulatory T cells share common epitope specificity but exhibit distinct T cell repertoire.
abstract: CD4(+) regulatory T cells (Tregs) accumulate at tumor sites and play a critical role in the suppression of immune responses against tumor cells. In this study, we show that two immunodominant epitopes derived from the tumor Ags (TAs) NY-ESO-1 and TRAG-3 stimulate both CD4+ Th cells and Tregs. TA-specific Tregs inhibit the proliferation of allogenic T cells, act in a cell-to-cell contact dependent fashion and require activation to suppress IL-2 secretion by T cells. TRAG-3 and NY-ESO-1-specific Tregs exhibit either a Th1-, a Th2-, or a Th0-type cytokine profile and dot not produce IL-10 or TGF-beta. The Foxp3 levels vary from one Treg clone to another and are significantly lower than those of CD4+CD25high Tregs. In contrast to NY-ESO-1-specific Th cells, the NY-ESO-1-specific and TRAG-3-specific Treg clonotypes share a common TCR CDR3 Vbeta usage with Foxp3+CD4+CD25high and CD4+CD25- T cells and were not detectable in PBLs of other melanoma patients and of healthy donors, suggesting that their recruitment occurs through the peripheral conversion of CD4+CD25- T cells upon chronic Ag exposure. Collectively, our findings demonstrate that the same epitopes spontaneously stimulate both Th cells and Tregs in patients with advanced melanoma. They also suggest that TA-specific Treg expansion may be better impaired by therapies aimed at depleting CD4+CD25high Tregs and preventing the peripheral conversion of CD4+CD25- T cells.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213-2582, USA.
authors.forename: Julien
authors.initials: J
authors.lastname: Fourcade
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Sun
authors.forename: Pavol
authors.initials: P
authors.lastname: Kudela
authors.forename: Bratislav
authors.initials: B
authors.lastname: Janjic
authors.forename: John M
authors.initials: JM
authors.lastname: Kirkwood
authors.forename: Talal
authors.initials: T
authors.lastname: El-Hafnawy
authors.forename: Hassane M
authors.initials: HM
authors.lastname: Zarour
mesh_terms: D000951:Antigens, Neoplasm / Q000276:immunology*; D002469:Cell Separation; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D008545:Melanoma / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell