Fetal calf serum (fcs)

Human multiple myeloma cells (MM1.S) and acute lymphoblastic leukemia cells (CEM-C7-14 and CEM-C1-15) were cultured in RPMI1640 glutamax (Gibco, life technologies) supplemented with 10% fetal calf serum (Greiner bio-one), 100U/mL penicillin and 0.1mg/mL streptomycin (Gibco, life technologies), and were grown in a 5% CO₂ incubator at 37°C. MM1.S cells were purchased from ATCC, CEM-C7-14 and CEM-C1-15 cells were kind gifts from Prof. Brad E. Thompson (University of Texas Medical Branch). Human embryonic kidney cells (HEK293T) and human lung carcinoma cells (A549) were cultured in DMEM (Gibco, life technologies) supplemented with 10% fetal calf serum (Greiner bio-one), 100U/mL penicillin and 0.1mg/mL streptomycin (Gibco, life technologies), and were grown in a 5% CO₂ incubator at 37°C. HEK293T and A549 cells were obtained from the nuclear receptor lab (NRL) (VIB-UGent). All experiments were performed using charcoal-stripped serum (Gibco, life technologies) to eliminate the influence of endogenous hormones present in fetal calf serum. All cell lines were regularly tested for mycoplasma contamination and were negative.
The glucocorticoid dexamethasone (Dex) was purchased from Sigma Aldrich and dissolved in EtOH. In all experiments the total solvent concentration was kept equal in each condition.

NK-92 cells (CRL-2407, ATCC, Manassas, VA, USA) were cultured in alpha Minimum Essential medium (Thermo Fisher Scientific, Waltham, MA, USA) without ribonucleosides and deoxyribonucleosides, supplemented with 2 mM L-glutamine, 2.2 g sodium bicarbonate (Sigma-Aldrich, Munich, Germany), 0.2 mM inositol (Sigma-Aldrich), 0.1 mM 2-mercaptoethanol (Sigma-Aldrich), 0.02 mM folic acid (Sigma-Aldrich), 100 U/mL recombinant IL-2 (Proleukin, Novartis, Basel, Switzerland), 12.5% horse serum (ATCC), 12.5% fetal calf serum (FCS, Greiner Bio-One, Frickenhausen, Germany), and 1% penicillin/ streptomycin (Thermo Fisher Scientific). K562 (ATCC CCL-243) cells were cultured in IMDM supplemented with 10% FCS (Greiner Bio-One) and 1% penicillin/streptomycin (Thermo Fisher Scientific). 293FT cells (R700-07, Thermo Fisher Scientific) were cultured in DMEM/high glucose medium supplement with 10% FCS (Greiner Bio-One), 0.1 mM MEM non-essential amino acids (NEAA, Thermo Fisher Scientific), 2 mM L-glutamine (Thermo Fisher Scientific), and 1 mM MEM sodium pyruvate (Thermo Fisher Scientific). The Jurkat cell line (ACC 282, DSMZ, Braunschweig, Germany) was cultured in RPMI-1640 medium (Thermo Fisher Scientific) with 10% FCS and 1% penicillin/streptomycin.

NK cells were isolated from fresh blood derived from healthy donors after signing informed consent or from healthy donor’s HLA-typed buffy coats. Donors with an HLA-C1+C2+Bw4+ genotype were selected. The use of buffy coats, being a by-product of a required Medical Ethical Review Committee (METC) procedure, does not need ethical approval in The Netherlands under the Dutch Code for Proper Secondary Use of Human Tissue. These buffy coats were anonymous, and the individuals from whom the samples originated did not object to their use. PBMCs were obtained by density gradient centrifugation of the donor sample using lymphoprep (Axis-Shield). NK cells were subsequently isolated by negative selection with an NK cell isolation kit using MACS beads and columns according to manufacturer’s protocol (Miltenyi Biotec, GmbH). For short-term activation, NK cells were cultured in RPMI-1640 medium (Gibco) supplemented with 10% fetal calf serum (Greiner Bio-One), 100 U/mL penicillin (Gibco) and 100 µg/mL streptomycin (Gibco) at 37 °C in humidified air containing 5% CO₂ with 21% O₂ (Sanyo MCO-20AIC, Sanyo Electric Co, Japan). NK cells were activated overnight with 1000 IU/mL recombinant human IL-2 (Proleukin, Novartis).