The CD11b+Ly6Chigh Mϕ (G1 in Fig. 7A), CD11b+Ly6Cint Mϕ (G2) or CD11b+Ly6C− Mϕ (G3) were sorted and then co-cultured with CD4+ T cells in anti-CD3/CD28 Ab-coated plates for 3 days. The CD11b+Ly6Chigh Mϕ almost completely suppressed CD4+ T-cell proliferation, while the CD11b+Ly6C− Mϕ did not (Fig. 7B). CD11b+Ly6Cint Mϕ also exhibited suppressive PD0325901 solubility dmso activity on T-cell proliferation, although this activity was significantly weaker than that

of CD11b+Ly6Chigh Mϕ. Furthermore, IFN-γ and IL-17 levels from the stimulated CD4+ T cells were decreased by co-culture with CD11b+Ly6Chigh Mϕ (Fig. 7C). In contrast to IFN-γ and IL-17, IL-4 levels were negligible in all cases (data not shown). HP is a pulmonary hypersensitivity reaction characterized by a massive lymphocyte infiltration into the lungs 12. It has been shown that T cells, especially Th1 cells, play a pivotal role in the pathogenesis of HP as indicated by increased levels of IFN-γ and IL-12 in the lung 14, 16. In addition to a Th1/Th2 imbalance, insufficient Treg function appears critical for the pathogenesis of HP, as blockade of co-stimulatory signals using CTLA4-Ig administration reduced pulmonary inflammation by decreasing specific auto-antibody and cytokine production 17. Previous results have shown that Gal-9 may induce apoptosis of Tim-3-expressing Th1 cells via

Gal-9/Tim-3 interaction 1, and that Gal-9 induces the up-regulation of Treg 7. Furthermore, highly pro-inflammatory IL-17-producing Th17 cells also express Tim-3 on their surfaces 3. In fact, Selleck BMS 354825 Gal-9 was found to decrease the number of Tim-3-expressing CD4 T cells and increase the number of CD4+CD25+Foxp-3+ Treg on days 3 and 7 of experimental HP, raising the hypothesis that Gal-9 suppresses

experimental HP, at least in part, by the above mechanisms in the late phase of experimental HP. Our results indicate Etofibrate that Gal-9 treatment suppressed experimental HP in vivo, based on the levels of IFN-γ and IL-17 in the BALF and on the clinical scores on day 1 post-challenge relative to PBS-challenged controls. Intriguingly, co-culture of T cells with BALF cells from Gal-9-treated mice on day 1 post-challenge suppressed T-cell proliferation and IFN-γ production after CD3 stimulation in vitro. We further found that CD11b+Ly-6ChighF4/80+ cells with monocyte/Mϕ morphology may be responsible for this suppression. It is well known that expansion of MDSC occurs in cancer patients and in tumor-bearing mice, and that these MDSC negatively affect T-cell expansion and effector functions 9–11. Expansion of MDSC has also been induced after exposures to bacterial 18, parasitic 19–21 and viral Ag 22, and after traumatic stress 23. Recent studies have also shown that MDSC are a group of myeloid cells comprised of precursors of macrophages, granulocytes, DC, and myeloid cells at earlier stages of differentiation 11, 23.