At 6 weeks, the methylcellulose medium was dissolved in PBS, and the cells were then
resuspended and cultured in Iscove’s modified Dulbecco’s medium supplemented with 100 ng/ml SCF, 50 ng/ml IL-6, 5% fetal calf serum, 55 μm 2-mercaptoethanol, buy INCB024360 100 IU/ml penicillin and 100 μg/ml streptomycin. Hemi-depletions of media were performed weekly by adding fresh media. The final purity of mast cells always exceeded 95%. Mast cells (2 × 105 cells/well) were suspended in Tyrode’s buffer [10 mm HEPES buffer (pH 7·4), 130 mm NaCl, 5 mm KCl and 5·6 mm glucose] containing 0·1% BSA, 1 mm CaCl2 and 0·6 mm MgCl2, then stimulated with various concentrations of catestatin peptides or diluent (0·01% acetic acid) for 40 min at 37°. The β-hexosaminidase levels in the supernatants and total cell lysates solubilized with Triton X-100 were quantified by hydrolysis of p-nitrophenyl-N-acetyl-β-d-glucopyranoside in 0·1 m sodium CH5424802 citrate buffer for 90 min at 37°. The percentage of β-hexosaminidase release was calculated as reported previously.15 In some experiments, inhibitors were added 2 hr
before stimulation, and β-hexosaminidase release was measured as described above. Mast cells (1 × 106 cells) were incubated with catestatins at the indicated concentrations for 0·5–24 hr at 37°. After stimulation, the cells were centrifuged, and the cell-free supernatants from cultures of stimulated mast cells or non-stimulated control cells were used for LTC4, PGD2 and PGE2 quantification by an EIA, while granulocyte macrophage colony-stimulating factor (GM-CSF), monocyte chemotactic protein (MCP-1)/CCL2, Thalidomide macrophage inflammatory protein 1α (MIP-1α/CCL3 and MIP-1β/CCL4 were measured using appropriate
ELISA kits according to the manufacturer’s instructions. In some experiments, inhibitors were added 2 hr before stimulation, and the EIA or ELISA quantification was performed as described above. Total RNA was extracted from mast cells using an RNeasy Micro kit (Qiagen, Venlo, the Netherlands). First-strand cDNA was then synthesized from 2 μg total RNA using a High-Capacity cDNA Reverse Transcription kit (Applied Biosystems) according to the manufacturer’s instructions. Quantitative real-time PCR was performed as reported previously,16 using TaqMan Universal PCR Master Mix (Applied Biosystems). Amplification and detection of mRNA were analysed using a 7500 Real-Time PCR System (Applied Biosystems) according to the manufacturer’s instructions.