title: Hematopoietic progenitor cell regulation by CD4+CD25+ T cells.
abstract: CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) possess the capacity to modulate both adaptive and innate immune responses. We hypothesized that Tregs could regulate hematopoiesis based on cytokine effector molecules they can produce. The studies here demonstrate that Tregs can affect the differentiation of myeloid progenitor cells. In vitro findings demonstrated the ability of Tregs to inhibit the differentiation of interleukin-3 (IL-3)/stem cell factor (colony-forming unit [CFU]-IL3)-driven progenitor cells. Inhibitory effects were mediated by a pathway requiring cell-cell contact, major histocompatibility complex class II expression on marrow cells, and transforming growth factor-beta. Importantly, depletion of Tregs in situ resulted in enhanced CFU-IL3 levels after bone marrow transplantation. Cotransplantation of CD4(+)FoxP3(+)(gfp) Tregs together with bone marrow was found to diminish CFU-IL3 responses after transplantation. To address the consequence of transplanted Tregs on differentiated progeny from these CFU 2 weeks after hematopoietic stem cell transplantation, peripheral blood complete blood counts were performed and examined for polymorphonuclear leukocyte content. Recipients of cotransplanted Tregs exhibited diminished neutrophil counts. Together, these findings illustrate that both recipient and donor Tregs can influence hematopoietic progenitor cell activity after transplantation and that these cells can alter responses outside the adaptive and innate immune systems.
authors.affiliation: Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA.
authors.forename: Maite
authors.initials: M
authors.lastname: Urbieta
authors.forename: Isabel
authors.initials: I
authors.lastname: Barao
authors.forename: Monica
authors.initials: M
authors.lastname: Jones
authors.forename: Roland
authors.initials: R
authors.lastname: Jurecic
authors.forename: Angela
authors.initials: A
authors.lastname: Panoskaltsis-Mortari
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Blazar
authors.forename: William J
authors.initials: WJ
authors.lastname: Murphy
authors.forename: Robert B
authors.initials: RB
authors.lastname: Levy
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology; D000818:Animals; D006410:Hematopoiesis / Q000276:immunology*; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology; D007377:Interleukin-3 / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000276:immunology; D014184:Transplantation, Homologous
chemical_list: D000949:Histocompatibility Antigens Class II; D007377:Interleukin-3; D016212:Transforming Growth Factor beta