- IL-2 stimulated but not unstimulated NK cells induce selective disappearance of peripheral blood cells: concomitant results to a phase I/II study (2011)
- In an ongoing clinical phase I/II study, 16 pediatric patients suffering from high risk leukemia/tumors received highly purified donor natural killer (NK) cell immunotherapy (NK-DLI) at day (+3) +40 and +100 post haploidentical stem cell transplantation. However, literature about the influence of NK-DLI on recipient's immune system is scarce. Here we present concomitant results of a noninvasive in vivo monitoring approach of recipient's peripheral blood (PB) cells after transfer of either unstimulated (NK-DLI(unstim)) or IL-2 (1000 U/ml, 9–14 days) activated NK cells (NK-DLI(IL-2 stim)) along with their ex vivo secreted cytokine/chemokines. We performed phenotypical and functional characterizations of the NK-DLIs, detailed flow cytometric analyses of various PB cells and comprehensive cytokine/chemokine arrays before and after NK-DLI. Patients of both groups were comparable with regard to remission status, immune reconstitution, donor chimerism, KIR mismatching, stem cell and NK-DLI dose. Only after NK-DLI(IL-2 stim) was a rapid, almost complete loss of CD56(bright)CD16(dim/−) immune regulatory and CD56(dim)CD16(+) cytotoxic NK cells, monocytes, dendritic cells and eosinophils from PB circulation seen 10 min after infusion, while neutrophils significantly increased. The reduction of NK cells was due to both, a decrease in patients' own CD69(−) NCR(low)CD62L(+) NK cells as well as to a diminishing of the transferred cells from the NK-DLI(IL-2 stim) with the CD56(bright)CD16(+/−)CD69(+)NCR(high)CD62L(−) phenotype. All cell counts recovered within the next 24 h. Transfer of NK-DLI(IL-2 stim) translated into significantly increased levels of various cytokines/chemokines (i.e. IFN-γ, IL-6, MIP-1β) in patients' PB. Those remained stable for at least 1 h, presumably leading to endothelial activation, leukocyte adhesion and/or extravasation. In contrast, NK-DLI(unstim) did not cause any of the observed effects. In conclusion, we assume that the adoptive transfer of NK-DLI(IL-2 stim) under the influence of ex vivo and in vivo secreted cytokines/chemokines may promote NK cell trafficking and therefore might enhance efficacy of immunotherapy.
- Histone deacetylase inhibitors enhance expression of NKG2D ligands in Ewing sarcoma and sensitize for natural killer cell-mediated cytolysis (2012)
- Background: Ewing sarcoma patients have a poor prognosis despite multimodal therapy. Integration of combination immunotherapeutic strategies into first-/second-line regimens represents promising treatment options, particularly for patients with intrinsic or acquired resistance to conventional therapies. We evaluated the susceptibility of Ewing sarcoma to natural killer cell-based combination immunotherapy, by assessing the capacity of histone deacetylase inhibitors to improve immune recognition and sensitize for natural killer cell cytotoxicity. Methods: Using flow cytometry, ELISA and immunohistochemistry, expression of natural killer cell receptor ligands was assessed in chemotherapy-sensitive/-resistant Ewing sarcoma cell lines, plasma and tumours. Natural killer cell cytotoxicity was evaluated in Chromium release assays. Using ATM/ATR inhibitor caffeine, the contribution of the DNA damage response pathway to histone deacetylase inhibitor-induced ligand expression was assessed. Results: Despite comparable expression of natural killer cell receptor ligands, chemotherapy-resistant Ewing sarcoma exhibited reduced susceptibility to resting natural killer cells. Interleukin-15-activation of natural killer cells overcame this reduced sensitivity. Histone deacetylase inhibitor-pretreatment induced NKG2D-ligand expression in an ATM/ATR-dependent manner and sensitized for NKG2D-dependent cytotoxicity (2/4 cell lines). NKG2D-ligands were expressed in vivo, regardless of chemotherapy-response and disease stage. Soluble NKG2D-ligand plasma concentrations did not differ between patients and controls. Conclusion: Our data provide a rationale for combination immunotherapy involving immune effector and target cell manipulation in first-/second-line treatment regimens for Ewing sarcoma.
- Efficient lysis of rhabdomyosarcoma cells by cytokine-induced killer cells : implications for adoptive immunotherapy after allogeneic stem cell transplantation (2010)
- Background: Rhabdomyosarcoma is the most common soft tissue sarcoma in childhood and has a poor prognosis. Here we assessed the capability of ex vivo expanded cytokine-induced killer cells to lyse both alveolar and embryonic rhabdomyosarcoma cell lines and investigated the mechanisms involved. Design and Methods: Peripheral blood mononuclear cells from six healthy donors were used to generate and expand cytokine-induced killer cells. The phenotype and composition of these cells were determined by multiparameter flow cytometry, while their cytotoxic effect against rhabdomyosarcoma cells was evaluated by a europium release assay. Results: Cytokine-induced killer cells efficiently lysed cells from both rhabdomyosarcoma cell lines. Antibody-mediated masking of either NKG2D molecule on cytokine-induced killer cells or its ligands on rhabdomyosarcoma cells (major histocompatibility antigen related chain A and B and UL16 binding protein 2) diminished this effect by 50%, suggesting a major role for the NKG2D molecule in rhabdomyosarcoma cell killing. No effect was observed after blocking CD11a, CD3 or TCRαβ molecules on cytokine-induced killer cells or CD1d on rhabdomyosar-coma cells. Remarkably, cytokine-induced killer cells used tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to activate caspase-3, as the main caspase responsible for the execution of apoptosis. Accordingly, blocking TRAIL receptors on embryonic rhabdomyosarcoma cell lines significantly reduced the anti-tumor effect of cytokine-induced killer cells. About 50% of T cells within the cytokine-induced killer population had an effector memory phenotype, 20% had a naïve phenotype and approximately 30% of the cells had a central memory phenotype. In addition, cytokine-induced killer cells expressed low levels of activation-induced markers CD69 and CD137 and demonstrated a low alloreactive potential. Conclusions: Our data suggest that cytokine-induced killer cells may be used as a novel adoptive immunotherapy for the treatment of patients with rhabdomyosarcoma after allogeneic stem cell transplantation.