title: Low-strength T-cell activation promotes Th17 responses.
abstract: We show that the strength of T-cell stimulation determines the capability of human CD4(+) T cells to become interleukin-17 (IL-17) producers. CD4(+) T cells received either high- (THi) or low (TLo)-strength stimulation via anti-CD3/CD28 beads or dendritic cells pulsed with superantigen in the presence of pro-Th17 cytokines IL-1β, transforming growth factor β, and IL-23. We found that TLo, but not THi, stimulation profoundly promoted Th17 responses by enhancing both the relative proportion and total number of Th17 cells. Titration of anti-CD3 revealed that low TCR signaling promoted Th17 cells, but only in the presence of anti-CD28. Impaired IL-17 production in THi cells could not be explained by high levels of Foxp3 or transforming growth factor β-latency-associated peptide expressed by THi cells. Nuclear factor of activated T cells was translocated to the nucleus in both THi and TLo cells, but only bound to the proximal region of the IL-17 promoter in TLo cells. The addition of a Ca(2+) ionophore under TLo conditions reversed the pro-Th17 effect, suggesting that high Ca(2+) signaling impairs Th17 development. Although our data do not distinguish between priming of naive T cells versus expansion/differentiation of memory T cells, our results clearly establish an important role for the strength of T-cell activation in regulating Th17 responses.
authors: Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK.
authors: Harriet A
authors: HA
authors: Purvis
authors: Jeroen N
authors: JN
authors: Stoop
authors: Jelena
authors: J
authors: Mann
authors: Steven
authors: S
authors: Woods
authors: Anne E
authors: AE
authors: Kozijn
authors: Sophie
authors: S
authors: Hambleton
authors: John H
authors: JH
authors: Robinson
authors: John D
authors: JD
authors: Isaacs
authors: Amy E
authors: AE
authors: Anderson
authors: Catharien M U
authors: CM
authors: Hilkens
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000276:immunology*; D002469:Cell Separation; D047369:Chromatin Immunoprecipitation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D015398:Signal Transduction / Q000276:immunology; D058504:Th17 Cells / Q000166:cytology* / Q000276:immunology