2.4. Flow cytometry.
The following reagents were from Biolegend and BD Horizon. Cells were labeled with anti-human surface antibodies as follows: CD4-FITC (RPA-T4; BioLegend), CD25-APC (BC96; BioLegend), CD127-PE (A019D5; BioLegend), PD1-BB700 (EH12.1; BD Horizon). Flow cytometry analyses were performed using BD FACS Calibur. Flow cytometric data were analyzed using FlowJo software. Our gating strategy primarily identified CD4+CD25+CD127-/lowand PD-1.