Cell culture
PBMCs were obtained from human peripheral blood using Ficoll-Paque PLUS (GE Healthcare, Sweden) density gradient centrifugation. Briefly, whole blood was diluted with equal volume of phosphate-buffered saline (PBS) and layered on top of Ficoll-Paque PLUS. After centrifugation, the PBMC layer was collected and washed twice with PBS. The cells were then resuspended in RPMI Medium Modified (Thermo Fisher Scientific, USA) supplemented with 10% heat-inactivated fetal bovine serum (FBS) (Thermo Fisher Scientific, USA) and 1% penicillin/streptomycin (Thermo Fisher Scientific, USA). PBMCs were cultured in a humidified incubator at 37°C with 5% CO2.