Cell sorting was carried out at the Cell Sorting Core Facility of the Hannover Medical School on FACSAria (BD), XDP or MoFlo (both Beckman Coulter) machines. cDNA was prepared using the μMACS One-Step cDNA kit see more and a ThermoMACS magnetic separator (both from Miltenyi Biotec) according to the manufacturer’s instructions. Validated intron-spanning primer sets were designed employing the Universal Probe Library Assay Design Centre (www.roche-applied-science.com). The following primer pairs were used: Foxp3 (5′-agaagctgggagctatgcag-3′, 5′-gctacgatgcagcaagagc-3′); CD25 (Il2ra) (5′-ccaacacagtctatgcaccaa-3′, 5′-agattctcttggaatcttcatgttc-3′); CD73
(5′-atgaacatcctgggctacga-3′, 5′-gtccttccacaccgttatcaa-3′); CD103 (Itgae variant 2) (5′-cctggaccactacaaggaacc-3′, 5′-ttgcagtccttctcgtaggg-3′); CTLA4 (5′-tcactgctgtttctttgagca-3′, 5′-ggctgaaattgcttttcacat-3′); Folr4 variant 2 (5′-gcctgccactcatctttga-3′, 5′-tcattgatagaagacccttgacc-3′); GzmB
(5′-gctgctcactgtgaaggaagt-3′, 5′-tggggaatgcattttaccat-3′); Hprt (5′-tcctcctcagaccgctttt-3′, 5′- cctggttcatcatcgctaatc-3′). Quantitative real-time PCR was performed using the Mouse Universal Probe Library, the LightCycler480 Akt inhibitor Probes Master Kit and a LightCycler480 (all from Roche) according to the manufacturer’s instructions. Integrated system software was used to obtain second derivative crossing point (CP) values, and relative mRNA levels were calculated using the Hprt housekeeping gene. CD8+ T cells were obtained from secondary lymphoid organs of Rag1−/−×OTI mice
by negative magnetic isolation (Invitrogen) if not indicated otherwise. In some cases, total cell suspensions from spleens and thymi, or sorted CD8+CD11c− splenocytes were used. To study the mechanisms of Foxp3 induction, 1×104 CD8+ T cells were seeded in 96-well round bottom plates and cultured in RPMI medium (10% FCS supplemented) containing 200 U/mL rhIL-2 (Roche) and 0.01 μg/mL OVA257–264 (Biosynthan). Some wells were additionally supplemented with 2 μg/mL α-CD28 (37.51; eBioscience), 10 nM RA (Sigma), 2 ng/mL rhTGF-β1 (Peprotech) or different combinations BCKDHB of the latter reagents. After 2 days, all wells were supplemented with 200 U/mL fresh rhIL-2, and Foxp3 expression was assessed by flow cytometry on day 4. Equal cell numbers and conditions were used when total cell suspensions were cultured, with the exception that 5×104 total thymocytes were initially seeded. BM-derived DC were generated using GM-CSF (hybridoma supernatant) and added at indicated ratios to CD8+ T cells in some experiments. For the generation of CD8+Foxp3+ T cells, 10 mL cultures were established in 10 cm dishes using 5×106 CD8+ T cells negatively isolated cells from spleens and lymph nodes of DEREG×Rag1−/−×OTI mice. Cultures were supplemented with IL-2, OVA257–264, TGF-β1 and RA at the same concentrations as described above. Two days later, 200 U/mL IL-2 was supplemented and on day 3 10 mL of fresh medium was added if necessary.