PBMC, 1 × 106, were stained using a total of 5 µg of AHG- AlexaFluor® 488; 5 µl of anti-CD4-Pacific Blue™ or allophycocyanin (APC) and 5 µl of either phycoerythrin (PE) or PE-cyanin 7 (Cy7™) anti-human CD25 for 20 min at room temperature (RT). The

fluorescence was acquired using a fluorescence activate cell sorter (FACS)Caliber (BD Bioscience). The CH5424802 concentration data were analysed using FlowJo software from Treestar (Ashland, OR, USA). First the gates were drawn using forward- and side-scatter. The lymphocyte population was then gated for the CD4+ lymphocytes. Thereafter, the CD4+ gated population was analysed further for CD25+ and AlexaFluor® 488–AHG binding population. TCC was isolated from pooled normal sera, as described previously [25]. An additional step

to purify TCC further was performed by subjecting the TCC to chromatographic separation on Superose™ 6 YK (GE Healthcare, Los Angeles, CA, USA). The TCC-containing fractions were examined for C9 polymerization Vadimezan price by monitoring the generation of the neo-epitope (using clone aE11) using an enzyme-linked immunosorbent assay (ELISA) system. The TCC-containing fractions were pooled, concentrated and then stored at −70°C. The non-lytic dose of TCC was determined by incubating 1 × 106 Jurkat cells with varying concentrations from 0·25 to 5 µg of protein for 4 h and monitoring of apoptosis and necrosis using Vybrant® Apoptosis Assay #3 from Invitrogen, as per the manufacturer’s suggested protocol. From these experiments a dose of 2·5 µg was considered optimal, as more than 95% cells remained viable with trypan blue dye and propidium iodide staining. The expanded human naive CD4+ T cells purified from normal donors were used; 1 × 106 cells were activated by placing in serum-free medium for 4 h and treated with ICs (2·0 µg) or ICs (2·0 µg) in the presence of non-lytic TCC (2·5 µg).

The cells were collected post-2 h and used directly for experiments. The 2 h time interval was selected based on our previous observation of the T cell activation in response to treatment with ICs and TCC [26]. Lysates from cells treated with various stimuli were prepared from 1 × 106 cells using 0·5 ml of radioimmunoprecipitation assay (RIPA) buffer (50 mm Tris-HCL; 1% NP40; 0·25% Na-deoxycholate; 1 mm tetraacetic Urease acid (EDTA); 1 mm phenylmethylsulphonyl fluoride (PMSF); 1 mm Na3VO4; 1 mm sodium fluoride (NaF); and 1 µg/ml each aprotinin, leupeptin, pepstatin). Thereafter, 2 µg of monoclonal anti-FcγRIIIA/B antibody was added to the lysates and this mixture was then incubated at RT for 1 h. A 50-µl suspension of Protein G sepharose beads in saline (PBS) was then added and the mixture was incubated further at 4°C overnight. Subsequently, the Protein G beads were washed with excessive RIPA buffer and suspended into 1X reducing loading buffer from Invitrogen. These samples were heated and beads were separated by centrifugation. Protein content of samples was measured with micro bicinchoninic acid method (Sigma).