Recent reports have shown that RP105-deficient B cells are defective in their response to TLR2 and TLR4 ligands, whereas it is likely that RP105/MD-1 positively regulate TLR2/TLR4 responses in B cells.39 In contrast, Divanovic et al.40 reported that RP105 negatively regulates LPS-induced responses in macrophages and dendritic cells.

In the present Selleck Obeticholic Acid study, we examined RP105 to ascertain the expression of innate immune-related molecules in B cells. The major population of peritoneal B cells has been well reported to be B-1a cells and the immune function of this subset is essentially different from that of the conventional B-cell subset (B-2 cells) that exists in other organs. The present results obtained by flow cytometry suggest that the major population of intestine-related B cells (MLNs, PPs, colon lamina propria) has a B-2 lineage. Next, we examined the production of IL-10 and TGF-β1 in TLR-mediated B see more cells. Mononuclear cells were isolated from several

parts of BALB/c mice and magnetically purified using microbeads. Next, purified B cells (B220+ PDCA-1−) were cultured with or without TLR ligands, then cytokine concentrations in the culture supernatants were measured by EIA. The B-cell fractions used in the experiments were confirmed to be > 95% pure by flow cytometry (Fig. 2a). Although IL-10 production was induced in TLR ligand-mediated B cells, the level of production in CpG-DNA-stimulated cells was significantly higher than that in LPS-stimulated cells (Fig. 2b). In addition, IL-10 production by TLR-mediated PerC B cells was remarkably higher than that by B cells isolated from other parts

of the mice. These results may have been dependent on the unique characteristics of PerC B cells derived from a B-1 lineage. However, when compared with the results of IL-10, lower production levels of TGF-β1 in response to TLR ligands were observed in all 3-mercaptopyruvate sulfurtransferase of the tested samples (Fig. 2b). In the body systems, TGF-β1 occurs in two physiological forms: latent and active. Although TGF-β1 is important in regulating crucial cellular activities, in most cases an activated TGF-β1 ligand will initiate the TGF-β1 signalling cascade. In our present system, the majority of TGF-β1 as assessed was solely inactive or latent. We also measured the active form of TGF-β1 but the amount was too low to demonstrate any effects of TLR ligands on their secretion (data not shown). Following our experimental results, we investigated the presence of a regulatory B-cell subset producing IL-10 and TGF-β1 in the intestines of BALB/c mice. Furthermore, we conducted additional experiments to elucidate the role of this intestinal regulatory B-cell subset in the pathogenesis of CD using SAMP1/Yit mice. Development of ileitis in the SAMP1/Yit mice was confirmed by histological examinations.