T-cell analyses were performed by fluorescence-activated cell sorting (FACS) using an LSRII or a FACS Calibur flow cytometer and the cell quest analysis program (BD Bioscience, Heidelberg, Germany). T-cell surface markers were directly stained with fluorescence-labeled mAbs against CD4 (clone RM4-5; BD Biosciences), CD8 (53-6.7, eBioscience, San Diego, USA), CD44 (IM7; BD Biosciences), CD62L (MEL-14; eBioscience) and CD69 (H1.2F3; BD Bioscience). Ki67 (SolA15; eBioscience), CTLA-4 (UC10-4B9; BioLegend, or HB304) and the transcription factor FoxP3 (FJK-16s; eBioscience) were stained intracellularly.