cd T cells are a potent source of innate IL-17A and IFN-c, and they acquire the capacity to produce these cytokines within the thymus. However, the precise stages and required signals that guide this differentiation are unclear. Here we show that the CD24 low CD44 high effector cd T cells of the adult thymus are segregated into two lineages by the mutually exclusive expression of CCR6 and NK1.1. Only CCR6 1 cd T cells produced IL-17A, while NK1.1 1 cd T cells were efficient producers of IFN-c but not of IL-17A. Their effector phenotype correlated with loss of CCR9 expression, particularly among the NK1.1 1 cd T cells. Accordingly, both cd T-cell subsets were rare in gut-associated lymphoid tissues, but abundant in peripheral lymphoid tissues. There, they provided IL-17A and IFN-c in response to TCR-specific and TCR-independent stimuli. IL-12 and IL-18 induced IFN-c and IL-23 induced IL-17A production by NK1.1 1 or CCR6 1 cd T cells, respectively. Importantly, we show that CCR6 1 cd T cells are more responsive to TCR stimulation than their NK1.1 1 counterparts. In conclusion, our findings support the hypothesis that CCR6 1 IL-17A-producing cd T cells derive from less TCR-dependent selection events than IFN-c-producing NK1.1 1 cd T cells.Key words: gd T cells . CCR6 . IFN-g . IL-17A . Innate lymphocytes . NK1.1 Introduction IL-17A and IFN-g are generally regarded as pro-inflammatory effector cytokines that can be produced by Th cells but also by innate lymphocytes such as NK cells, NKT cells and gd T cells. While macrophage activation is supposed to be the main role of IFN-g, the induction of granulopoiesis is ascribed as a key biological function of IL-17A [1]. It is currently emerging that gd T cells are a potent source of IL-17A in the early phases of immune responses (reviewed in [2]). gd T cells constitute a large fraction of all IL-17A-producing cells in healthy mice and humans and are able to secrete IL-17A much more rapidly than CD4 1 Th17 cells [3][4][5]. These observations led to the concept that gd T cells are important players in a transitional response between innate and adaptive immune reactions [6]. The production of innate IL-17A by gd T cells appears to be essential in situations where an effective defence against extra-cellular bacteria or fungi relies on the fast mobilization of neutrophils [4,[6][7][8][9]. Moreover, IL-17A-producing gd T cells have been described to play important roles in immunopathologic diseases such as collageninduced arthritis [10], experimental pulmonary fibrosis [11], and in experimental autoimmune encephalitis [12,13].In contrast to CD4 1 Th cells that can develop into Th17 cells after encounter of specific cognate TCR Ag [14][15][16], it is not clear which stimuli induce IL-17A production by gd T cells in vivo. This essentially results from a lack of information about physiological gd TCR ligands. However, the current literature suggests that the decision whether a gd T cell will produce IL-17A is linked to 3488thymic development. Jensen et al. introduced a concept th...

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Estimates of relative efficacy between alternative treatments are crucial for decision making in health care. Bayesian mixed treatment comparison models provide a powerful methodology to obtain such estimates when head-to-head evidence is not available or insufficient. In recent years, this methodology has become widely accepted and applied in economic modelling of healthcare interventions. Most evaluations only consider evidence from randomized controlled trials, while information from other trial designs is ignored. In this paper, we propose three alternative methods of combining data from different trial designs in a mixed treatment comparison model. Naive pooling is the simplest approach and does not differentiate between-trial designs. Utilizing observational data as prior information allows adjusting for bias due to trial design. The most flexible technique is a three-level hierarchical model. Such a model allows for bias adjustment while also accounting for heterogeneity between-trial designs. These techniques are illustrated using an application in rheumatoid arthritis.

Induced antigen-specific Foxp3 1 T cells (iTreg) are being discussed as a promising alternative to polyclonal natural Foxp3 1 T cells (nTreg) for cell-based therapies, particularly to achieve transplantation tolerance. Using Foxp3eGFP-reporter mice, we here establish an efficient protocol to induce and expand alloantigen-specific iTreg from Foxp3 À CD4 1 T cells with cluster-disrupted DC. These iTreg were mainly CD62L 1 and showed efficient suppressive activity in vitro. However, in contrast to nTreg, adoptively transferred iTreg entirely failed to prevent lethal graft versus host disease (GVHD). Within irradiated recipients, the majority of adoptively transferred Foxp3 1 iTreg, but not Foxp3 1 nTreg quickly reverted to Foxp3 À CD4 1 T cells. We therefore suggest that therapeutic approaches to treat GVHD should rely on nTreg, whereas the use of de novo alloantigen-induced iTreg should be handled with caution since the stability of the regulatory phenotype of the iTreg could be of major concern.Key words: Animal models . Dendritic cells . Graft rejection . Regulatory T cells See accompanying article by commentary by Edinger IntroductionRecent advances have demonstrated that adoptively transferred exogenous Treg can inhibit graft versus host disease (GVHD) [1][2][3]. However, the availability of sufficient numbers of donor Treg for cell-based therapies remains limited [4]. Besides the in vitro expansion of nTreg [5], an obvious approach to solve this problem would be the de novo induction and expansion of Foxp3 1 Treg from abundant naïve CD4 1 T cells with recipient alloantigens [6,7]. Instead of mediating unspecific suppression, such alloantigen-induced Treg potentially could provide the advantage of antigen-specific regulation, thereby reducing the risk of disease relapse and infections [8]. Here, we present an efficient protocol to induce Foxp3 1 Treg by the use of clusterdisrupted allogeneic DC. Such allo DC-induced iTreg were functionally active in vitro and displayed a stable regulatory phenotype upon adoptive transfer into untreated syngeneic recipients. However, when used in experimental acute GVHD, these cells quickly lost Foxp3 expression and, in contrast to nTreg, did not show any protective effect. SHORT COMMUNICATION Results and discussionTo define conditions suited for the de novo induction of alloantigen-specific iTreg, we isolated Foxp3 À CD4 1 T cells from C57BL/6 Foxp3EGFP mice and co-cultured them with BM-derived allogeneic BALB/c DC that were either matured by application of LPS or via ''cluster-disruption'' (CD-DC). Disruption of the Ecadherin-mediated cell-cell contacts induces DC maturation through mechanisms distinct from TLR signaling [9]. Since antigen-loaded CD-DC have been shown to induce tolerance in mice after i.v. injection [9] we established a protocol that allowed the conversion of naïve to Foxp3 expressing cells in vitro in the presence of allogeneic but not syngeneic CD-DC. When compared with LPS-matured DC, CD-DC showed equally high expression of MHC class II, but diminished up...

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The chemokine receptor CCR7 represents an important determinant for circulating lymphocytes to enter lymph nodes (LN) via high endothelial venules. High endothelial venules also represent the major site of entry for plasmacytoid dendritic cells (pDC). In the steady-state, murine pDC have been suggested to home to LN engaging the chemokine receptors CXCR3, CXCR4, and CCR5, whereas responsiveness to CCR7 ligands is thought to be acquired only upon activation. In this study, we show that already resting pDC express minute amounts of CCR7 that suffice to trigger migration to CCL19/CCL21 in vitro. Upon activation with TLR ligands, CCR7 levels on pDC are strongly increased. Notably, CCR7-deficient mice display substantially reduced pDC counts in LN but not in bone marrow and spleen. Adoptive cell transfer experiments revealed that under both steady-state as well as inflammatory conditions, the homing of CCR7-deficient pDC is severely impaired, indicating that the reduced cell counts of naive pDC observed in CCR7−/− mice reflect an intrinsic homing defect of pDC. Together, these observations provide strong evidence that similar to naive lymphocytes, nonstimulated pDC exploit CCR7 to gain entry into LN. This adds to the repertoire of chemokine receptors permitting them to enter diverse tissues.