Expression and purification of recombinant proteins was essentially the same as previously described (10, 12). Briefly, E. coli BL21 (DE3) cells harboring plasmid pET28a-S450–650, pET28a-CRT, or pET28a-S450–650/CRT were cultured in 1L 2YT medium containing kanamycin (30 μg/mL) at 37 °C. When the cell density had reached 0.8–1.0 (optical density 600), IPTG (Sigma-Aldrich, St Louis, MO, USA) was added to a final concentration of 0.1 mM, and the bacteria cultured for a further 3.5 hr at 37 °C. The culture was then harvested

by centrifugation and the cell pellet suspended in 40 mL binding buffer (500 mM NaCl, 20 mM Tris-HCl, 5 mM imidazole, pH 7.9). After sonication (4 s pulse, 4 s pause, 200 W 50 times), the lysed cells were centrifuged at 5000 g for 15 min at 4 °C. The supernatant was incubated with 2

mL Ni sepharose (GE Healthcare, Uppsala, Sweden) at 4 selleckchem °C for 1 hr. The sepharose was poured into a column and washed with 100 mL wash buffer (500 mM NaCl, 20 mM Tris-HCl, 20 mM imidazole, pH 7.9) and then the recombinant protein eluted with elute buffer (500 mM NaCl, 20 mM Tris-HCl, 500 mM imidazole, pH 7.9). The final products were dialyzed with PBS (pH 7.2) and stored at −20°C before use. S450–650-based ELISAs were performed according to the protocol previously described (8, 9). Briefly, ELISA plates were coated at 4 °C overnight with 2 μg/mL rS450–650 in carbonate buffer (pH 9.6). The wells selleck products were then incubated with 2% BSA in PBS for 2 hr at 37 °C, and then washed five times with PBST. Serum samples from immunized mice were diluted in dilution buffer (0.1% BSA in PBS). 100 μL of each dilution was added to each well and the plates incubated for 90 min at 37 °C. After washes with PBST, the Protein kinase N1 plates were incubated with 100 μL HRP-labeled goat anti-mouse IgG, IgG1 or IgG2a antibody (Southern Biotech, Birmingham, AL, USA) 1/4000 diluted in dilution buffer for 1 hr at 37 °C. OPD substrate (100 μL /well) was added after five washes with PBS-T and incubated at room temperature. 50 μL of 2M H2SO4 solution was

added to each well to stop the reaction, and the optical density was immediately read at 492 nm. Bone marrow was flushed out of the femora and tibiae of BALB/c mice and incubated at a starting concentration of 5 × 106 cells/mL in R10 medium in 6-well flat bottomed plates (Falcon, Oxnard, CA, USA) at 37 °C, 5% CO2 for 3 hr. Non-adherent cells were removed before recombinant mouse GM-CSF (rmGM-CSF, PeproTech EC, London, UK) was added to the culture (20 ng/mL). On day 3, half of the medium was replaced with fresh medium containing rmGM-CSF. On day 5, adherent cells were harvested as bone-marrow-derived immature DCs and examined microscopically and also by flow cytometry for expression of CD11c.