Collection (Manassas, VA). HK-2 cells were cultured in RPMI 1640 (Sigma-Aldrich, St. Louis, MO) supplemented with 10% fetal bovine serum (FBS) (Invitrogen, Grand Island, NY) and 1% penicillin and streptomycin (Invitrogen). PBMCs were obtained from three healthy donors, after obtaining informed consent, using Ficoll-gradient sedimentation. PBMCs were cultured with RPMI 1640 (Sigma-Aldrich) supplemented with 10% FBS (Invitrogen) and 1% penicillin and streptomycin (Invitrogen).