All human cell lines were cultured in RPMI-1640 supplemented with 10% fetal bovine serum (FBS) (from here on termed R10) or in the recommended medium. The following cell lines were used: T2, THP-1, and HS-5 (from American Type Culture Collection, Manassas, VA, USA); Set-2, OCI-AML2, OCI-AML3, and U2940 (from Deutsche Sammlung von Mikroorganismen und Zellkulturen, Braunschweig, Germany); PB2B and MAC-2A (a kind gift from Niels Ødum, University of Copenhagen, Denmark); K562 cells stably transduced with HLA-A2 or HLA-A3; K562-A2 and K562-A3 (a kind gift from Mariam Heemskerk, University Hospital Leiden, The Netherlands); Marimo (a kind gift from Steffen Koschmieder, Universitätsklinikum Aachen, Germany); and UKE-1 (a kind gift from W. Fiedler, University Hospital of Eppendorf, Germany). PB2B and MAC-2A were from cutaneous lymphoma; Marimo, OCI-AML2, OCI-AML-3, THP-1, Set-2, and UKE-1 from acute myeloid leukemia (AML); and U2960 from diffuse large B cell lymphoma. The murine cancer cell line EO771.LMB (a kind gift from Janine Erler, University of Copenhagen, Denmark, and originally described by Johnstone et al.28 (link)) was maintained in Dulbecco’s modified Eagle´s medium (DMEM) with 20% FBS, 20 mM HEPES, and penicillin and streptomycin (Pen/Strep) to a final concentration of 100 U/ml and 100 μg/ml, respectively. All cell lines were tested and confirmed negative for mycoplasma.