TY - JOUR T1 - Human NK-92 Cells Function as Target Cells for Human NK Cells – Implications for CAR NK-92 Therapies JF - Anticancer Research JO - Anticancer Res SP - 5355 LP - 5359 DO - 10.21873/anticanres.14543 VL - 40 IS - 10 AU - HANS BERGMAN AU - NOORA SISSALA AU - HENRY HÄGERSTRAND AU - CHRISTER LINDQVIST Y1 - 2020/10/01 UR - http://ar.iiarjournals.org/content/40/10/5355.abstract N2 - Background/Aim: Recent studies indicate that chimeric antigen receptor (CAR)-T-cells seem to be superior to CAR modified NK-92 cells. One, at least partial, explanation to this discrepancy has been addressed herein, by having NK-92 cells as target cells in cytotoxicity reactions using peripheral blood mononuclear cells. Materials and Methods: A time-resolved fluorometric assay (TDA-labeled NK-92 or K562 as target cells) was used for measuring the cytotoxic activity of blood mononuclear cells (PBMC). Results: The cytotoxic capacity of the NK-92 cells was initially demonstrated by their ability to efficiently kill K562 cells. Interestingly, having PBMC as effector cells rendered the very same NK-92 cells sensitive to NK-cell mediated cytolysis. A 1:100 target:effector ratio gave 34.1% lysis compared to 72.2% lysis for K562 cells. Incubating PBMC for longer times (24 up to 48 h) potentiated their NK-activity against NK-92 cells even more, reaching a level close to that obtained with K562 cells. Conclusion: This study pinpoints a severe problem that has to be considered in future immune-based cancer therapies with NK-92 as well as CAR-transduced NK-92 cells. ER -