Isolation of peripheral blood mononuclear cells
Whole blood samples from recovered patients and controls were collected in heparin-coated blood tubes. Peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll density gradient centrifugation as previously described.[34] Isolated PBMCs were cryo-preserved in storage medium containing 90% heat-inactivated fetal bovine serum (FBS; Gibco, Thermo Fisher Scientific, Inc., Waltham, MA) and 10% cell culture grade DMSO (Sigma Aldrich, Merck, Germany). Samples were stored in liquid nitrogen until batch recovery for the assays.