Primary cells

Apheresis collection was performed at the Institute of Transfusion Medicine and Organ Engineering (Hannover Medical School). Peripheral blood mononuclear cells (PBMCs) of Donors 1 and 3 were purified by sediment centrifugation (Ficoll, Biochrome AG, Berlin, Germany) and cryopreserved, whereas the cells of Donor 2 were not purified prior to cryopreservation. PBMCs were cultured in RPMI with 10% FBS and 1× P/S and supplemented with interleukin (IL)-7 (5 ng/ml) and IL-15 (5 ng/ml) (both from Miltenyi Biotec, Bergisch Gladbach, Germany). Media and cytokines were exchanged every 2 to 3 days.