title: Dendritic cells partially abrogate the regulatory activity of CD4+CD25+ T cells present in the human peripheral blood.
abstract: The factors that influence the functionality of human CD4(+)CD25(+) regulatory T cells are not well understood. We sought to characterize the effects of dendritic cells (DCs) on the in vitro regulatory activity of CD4(+)CD25(+) T cells obtained from peripheral blood of healthy human donors. Flow cytometry showed that a higher proportion of CD4(+)CD25(+(High)) T cells expressed surface glucocorticoid-induced tumor necrosis factor receptor family-related protein (GITR) and CTL-associated antigen 4 than CD4(+)CD25(-) or CD4(+)CD25(+(Med-low)) T cells. Intracellular Foxp3 was equivalently expressed on CD4(+)CD25(+(All)), CD4(+)CD25(+(High)), CD4(+)CD25(+(Med-low)) and CD4(+)CD25(-) T cell populations, irrespective of GITR and CTL-associated antigen 4 expression. CD4(+)CD25(+) T cells were isolated and then cultured in vitro with CD4(+)CD25(-) responder T cells and stimulated with anti-CD3 antibodies, and immature dendritic cells (iDCs), mature dendritic cells (mDCs), PBMCs or PBMCs plus anti-CD28 antibodies to provide co-stimulation. In addition, secretion of the T(h)1 cytokine IFN-gamma, IL-2 and the immunoregulatory cytokines, IL-10 and transforming growth factor (TGF)-beta, were also assessed in these cultures. We found that iDCs and mDCs were capable of reversing the suppression of proliferation mediated by CD4(+)CD25(+) regulatory T cells. However, the reversal of suppression by DCs was not dependent upon the increase of IFN-gamma and IL-2 production or inhibition of IL-10 and/or TGF-beta production. Therefore, DCs are able to reverse the suppressive effect of regulatory T cells independent of cytokine production. These results suggest for the first time that human DCs possess unique abilities which allow them to influence the functions of regulatory T cells in order to provide fine-tuning in the regulation of T cell responses.
authors.affiliation: Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
authors.forename: Justin S
authors.initials: JS
authors.lastname: Ahn
authors.forename: Deepa K
authors.initials: DK
authors.lastname: Krishnadas
authors.forename: Babita
authors.initials: B
authors.lastname: Agrawal
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000032:analysis; D000943:Antigens, Differentiation / Q000032:analysis; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D060908:CTLA-4 Antigen; D002450:Cell Communication / Q000187:drug effects / Q000276:immunology* / Q000528:radiation effects; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000528:radiation effects; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000032:analysis; D053450:Glucocorticoid-Induced TNFR-Related Protein; D006801:Humans; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000528:radiation effects; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D011070:Poly I-C / Q000494:pharmacology; D017475:Receptors, Nerve Growth Factor / Q000032:analysis; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D017252:CD3 Complex; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D016207:Cytokines; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D053450:Glucocorticoid-Induced TNFR-Related Protein; C508609:IL10 protein, human; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D008070:Lipopolysaccharides; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C491405:TNFRSF18 protein, human; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D007371:Interferon-gamma; D011070:Poly I-C