P38 inhibitor (SB 203580) and JNK inhibitor (SP 600125) were purchased from Sigma-Aldrich. Phycoerythrin (PE)-conjugated mouse monoclonal antibody (mAb) to FasL (IgG1 isotype) was purchased from

BioLegend (San Diego, CA, USA). Fluorescein isothiocyanate (FITC)-conjugated goat polyclonal anti-rabbit IgG was purchased from Santa Cruz Biotechnology. Cyanine 3 (Cy3)-conjugated rabbit polyclonal anti-goat IgG was purchased from Chemicon International (Temecula, CA, USA). Mammalian protein extraction reagent (M-PER) PI3K inhibitor and Restore Western blot stripping buffer were purchased from Pierce (Rockford, IL, USA). Immun-Star™ HRP chemiluminescent kit was purchased from Bio-Rad. PHA was obtained from Sigma-Aldrich. All media used for cell culture were negative for endotoxin as detected by Limulus amoebocyte lysate assay (Sigma-Aldrich), which had a sensitivity of approximately 0·05–0·1 ng of Escherichia coli lipopolysaccharide (LPS) per ml. The human MonoMac6 cell line [20] (DSMZ ACC click here 124) was obtained from the German Collection of Microorganisms and Cell Culture. Cells were maintained in RPMI-1640 with l-glutamine medium supplemented with 10% FCS and antibiotics (100 U/ml penicillin and 100 µg/ml streptomycin) at 37°C and 5% CO2. GXM was isolated from the culture supernatant

fluid of serotype A strain (CN 6) grown in liquid synthetic medium in a gyratory shaker for 4 days at 30°C. GXM was isolated by differential precipitation with ethanol and hexadecyltrimethyl ammonium bromide (Sigma-Aldrich) [21]; the procedure has been described in detail previously [22]. Soluble GXM isolated by the above procedure contained < 125 pg LPS/mg of GXM as detected by Limulus amoebocyte lysate assay (QCl-1000; BioWhittaker, Walkersville, MD, USA). MonoMac6 (1 × 106/ml) cells were incubated with antibody to FcγRIIB (0·1 µg/ml) or irrelevant goat polyclonal IgG (0·1 µg/ml) for 30 min at 4°C in RPMI-1640, or in the presence

and absence of JNK inhibitor SP 600125 (0·5 µM) or p38 inhibitor SB 203580 (1 µM) 4��8C for 30 min at 37°C, and then incubated in the presence and absence of GXM (100 µg/ml) in RPMI-1640 for 2 h at 37°C with 5% CO2. After incubation, cells were collected by centrifugation, fixed in 1% paraformaldehyde in phosphate-buffered saline (PBS) for 10 min at room temperature, washed twice with PBS containing 0·5 % bovine serum albumin (BSA) and 0·4% sodium azide (fluorescence buffer, FB) and stained with PE-labelled mAb to FasL (20 µl/106 cells) in FB for 40 min on ice. After incubation, the cells were washed twice with FB, then 5000 events were analysed by fluorescence activated cell sorter (FACScan) (BD Biosciences). Autofluorescence was assessed using untreated cells.