coli and assessed its cytotoxicity on DCs because the purified OmpA-sal was derived from S. enterica serovar Typhimurim. DCs were treated with various concentrations of OmpA-sal for 24 h. There were no statistically significant differences in the percentages of dead cells in DC cultures exposed to as much as 800 ng/ml of OmpA-sal, the concentration at which cell death was detected by annexin V/PI staining (Fig. 1A). This indicated that our recombinant OmpA-sal was not cytotoxic to DCs and did not contain

amounts of endotoxin that would interfere with our studies using concentrations < 400 ng/ml. Selleckchem TPX-0005 To determine the effects of OmpA-sal on the maturation of sentinel DCs into effector DCs, BM-derived DCs were cultured with GM-CSF and IL-4 for 6 days under standard conditions, followed by 1 PI3K inhibitor day in the presence of 100, 200, and 400 ng/ml of OmpA-sal. LPS was used as a positive control. The resulting populations of DCs were analyzed by flow cytometry for expression of co-stimulatory molecules involved in T cell activation. OmpA-sal-treated

DCs had increased expression of DC maturation co-stimulatory markers (DC80, CD86, MHC class I, and MHC class II; Fig 1B). Interestingly, the expression of CD86 and MHC class II by OmpA-sal-treated DCs was higher than LPS-treated DCs. These results indicated that OmpA-sal induces DC maturation in a dose-dependent manner. Figure 1 OmpA-sal is not cytotoxic and induces the expression of co-stimulatory molecules in DCs. BM-DCs were cultured for 24 h in the presence of 200 ng/ml of LPS or 100, 200, 400, and 800 ng/ml of OmpA-sal and analyzed Sirolimus mouse by flow cytometry. The DCs were stained with annexin V and PI. The percentage of positive cells is indicated (A). The cells were gated to exclude CD11c+ cells. Medium, untreated control; LPS, positive control. DCs were stained with anti-CD80, anti-CD86, anti-MHC class I, and anti-MHC

class II molecules (B). The data are representative of three experiments that yielded similar results. OmpA-sal reduces the endocytic activity of DCs Immature DCs are efficient in the capture and endocytosis of antigens. These cells can internalize large amounts of Bleomycin purchase antigen through each fluid-phase uptake via macropinocytosis and receptor-mediated uptake. However, in the case of mature DCs, the capacity to capture antigen and confer potent co-stimulatory activity for T cells is decreased [13]. We investigated whether OmpA-sal-treated DCs had reduced endocytic activity characteristic of functionally mature DCs. As shown in Fig. 2A, the percentage of double-positive cells was lower in the LPS-treated DCs than in the untreated DCs. Similarly, the percentage of double-positive cells was lower in the OmpA-sal-treated DCs compared with untreated DCs. These data show that the OmpA-sal-treated DCs had reduced endocytic activity, which indicates functional maturity.