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.