An alternative way to suppress the Th2 response via CD8+T cells in an IL-10-dependent manner could be through the activation of natural CD4+CD25+FoxP3+T cells [31]. in thein vivoregulation of Th2-type pathology. In this setting, we conclude that neonatal alloimmunization induces the expansion of several regulatory CD8+T cells Fangchinoline which may control Th2 activities via IFN- and IL-10. Keywords:IFN-, IL-10, neonates, regulatory CD8 T cells, Th2 == Introduction == Pioneering experiments by Billingham and colleagues [1] established that transplantation tolerance across major histocompatibility complex (MHC) class I and class II barriers can be induced by neonatal inoculation of semi-allogeneic spleen cells. Deletion of donor-specific T cells was considered for several years to be the dominant mechanism for such unresponsiveness to specific antigens [2]. Subsequent studies recognized immunodeviation [35] and immunoregulation [68] as the crucial underlying mechanisms of this neonatal tolerance. Indeed, CD4+T cells recognizing donor MHC class II antigens actually differentiate into T helper type 2 (Th2) cells in tolerant mice [35]. The consequence of this Th2 response is the development of an immunopathological syndrome which includes immunoglobulin (Ig)E overproduction, lymphoid organ hyperplasia, hypereosinophilia and increased production of Th2-type cytokines interleukin (IL)-4, IL-5, IL-13 and IL-10 [9,10]. Concerning donor-specific CD8+T cells, the inability of neonatally tolerant mice to generate effector cytotoxic T cell activity was well established [11,12] but the mechanism by which functional CD8+T cells may influence the unbalanced CD4+T cells in early life is less explored. Indeed, it has been established in several experimental models that CD8+T cells inhibit Th2 responses in adult animals [1317]. Major effort still needs to be invested in order to characterize phenotypically those regulatory CD8+T cells in early life, understand their effector mechanisms and the specificity of their effector phase. In this study we sought to characterize further the Fangchinoline phenotype and effector mechanisms of regulatory CD8+T cells occurring in the context of neonatal injection of allogeneic spleen cells. An important finding of this study is the demonstration that a subset of CD8+T cells expressing Rabbit Polyclonal to GPR174 CD25 displays a CD44highCD62Lhighmemory phenotype and expresses forkhead box P3 (FoxP3) at an early stage after neonatal immunization. We further demonstrate the crucial roles played by IFN- and IL-10, which are produced by these regulatory CD8+T cells in down-regulation of the Th2 responses. == Materials and methods == == Mice == BALB/c (H-2d) and C57BL/6 (H-2b) mice were obtained from Harlan (Zeist, the Netherlands). BALB/c 2-microglobulin (2m/) was kindly provided by Dr J.-C. Gury (Toulouse, France). A/J (H-2k), BALB/c IFN–deficient mice (IFN-/) and BALB/c IL-10-deficient mice (IL-10/) were purchased from Jackson Laboratories (Bar Harbor, ME, USA), and along with (A/J BALB/c)F1hybrids were housed and bred in our specific pathogen-free animal facility. == In vivotreatments == Neonatal tolerance was induced in BALB/c mice by injection into the retro-orbital vein of 107(A/J BALB/c)F1hybrid spleen cells within the first 24 h of life. For neonatal CD8+T cell transfer experiments, 1 106CD8+T cells were injected intravenously (i.v.) along with the F1spleen cells into 2m/BALB/c newborns. == Cell staining and flow cytometry analysis == Total lymph node (LN) cells were membrane-stained in fluorescence activated cell sorter (FACS) buffer [phosphate-buffered saline (PBS) 1, 05 % bovine serum albumin (BSA) serum 96% lyophilized powder] for 20 min at 4C with the following conjugated antibodies: Pacific blue- or fluorescein isothiocyanate (FITC)-conjugated anti-CD8 monoclonal antibody (mAb), FITC-conjugated anti-CD62L mAb, phycoerythrin-cyanin 5 (PE-Cy5)-conjugated anti-CD44 mAb and allophycocyanin (APC)-conjugated anti-CD25 mAb, biotinylated anti-CD28 and anti-CD127 mAb, PE-conjugated anti-H-2KkmAb and APC-Cy7- or PE-conjugated streptavidin were purchased from BD Biosciences (Erembodegem, Belgium). Data were obtained on a CyAnTM ADP LX9 flow cytometer and analysed using Summit version 42 software (DakoCytomation, Carpinteria, CA, USA). For intracellular cytokine staining, cells were stimulated with 50 ng/ml phorbol myristate acetate (PMA), 500 ng/ml Fangchinoline ionomycin and 1 g/ml Golgi Plug (BD Biosciences) for 4 h at 37C or left unstimulated. After washing, cells were incubated for 10 min with Fc blocking mAb (24G2; BD Biosciences), labelled for surface markers, fixed and permeabilized in CytoFix/CytoPerm solution (BD Biosciences), washed with Perm/Wash buffer (BD Biosciences), and finally labelled with specific cytokine or FoxP3 mAbs or isotype controls. Anti-FoxP3-PE (eBioscience, Hatfield, UK), anti-IFN–FITC (BD Biosciences), anti-IL-10-APC mAbs (BD Biosciences) Fangchinoline and isotype control were used according to the manufacturer’s instructions. For FoxP3 intracellular staining alone in CD8+CD25+cells, the eBioscience FoxP3 staining buffer was used for fixation and permeabilization. == Cell purification == CD4+T cells were purified from 68-week-old BALB/c wild-type.
An alternative way to suppress the Th2 response via CD8+T cells in an IL-10-dependent manner could be through the activation of natural CD4+CD25+FoxP3+T cells [31]