Control (WT) and KO thymocytes were labeled with different concentrations of CFSE, mixed at a 1:1 ratio and subsequently injected directly into the thymus of a PD0325901 price C57BL/6 recipient mouse, at a dose of 4 × 106 cells/mouse, and analyzed 3 days later for developmental progression. CD4+ or CD8+ T cells were
sorted by negative selection using CD4+ T and CD8+ T cell kits and magnetized columns (Miltenyi Biotech) according to the manufacturer’s specifications. Briefly, cells were labeled with biotin-conjugated antibodies (against CD8a (or CD4), CD11b, CD11c, CD19, B220, DX5, CD105, Ter119, and anti-MHC class II) followed by binding to antibiotin beads. The labeled cells were passed through magnetized columns to deplete all non-CD4+ or non-CD8-α+ T cell fractions, thus resulting in purified CD4+ or CD8+ T-cell populations. Subsequently, the purified cells were washed with sorting buffer (PBS supplemented with 2 mM EDTA and 2% FCS), followed by counting and resuspension in DMEM-10 media or PBS. A proliferation assay using thymidine incorporation was carried out as described  with minor modifications. Sorted cells were used at a concentration of 1 × 105 cells per well together with 2 × 105 cells per well of irradiated (2000 rads) splenocytes and appropriate stimuli at indicated doses for 3 days. A total of 1 μCi 3H-thymidine was applied to each well
for the last 18–20 h of the 3-day culture period. After cell culture, cells were harvested with the FilterMate Universal Harvester (PerkinElmer, Sheleton, CT, USA) on glass fiber filters (Wallac) and counted with MicroBeta Trilux 1450 LSC (PerkinElmer) STA-9090 in vitro using dedicated software. In CFSE assays, sorted cells were stained with 2 μM CFSE and incubated Interleukin-3 receptor for 72 h with appropriate stimuli at indicated doses. After incubation, CFSE-labeled cells were stained with appropriate antibodies and CFSE dilution within Vα2 positive cells was analyzed using a FACS Calibur cytometer. For adoptive transfer of transgenic T cells the experiments
were performed as previously described  with minor modifications. C57BL/6 mice were first immunized in the footpad with OVA protein or with OVA-coated beads in the presence of CFA followed by adoptive transfer of 5 or 10 × 106 cells (labeled with CFSE) from OT1 and OT2 transgenic mice, respectively. Three days after transfer, the proliferation of CFSE-labeled cells in the draining lymph node, within Vα2 positive cells, was analyzed by FACS. For evaluation of homeostatic cell expansion, purified OT1 or OT2 cells stained with CFSE were injected i.v. into RAG recipients (on the C57BL/6 background). The RAG recipients were left untreated for 2 weeks and splenocytes were harvested and analyzed. The proliferation of CFSE-labeled Vα2+ cells was analyzed by FACS and the absolute cell number of Vα2+ and CFSE+ DP cells was calculated.