title: Efficient lysis of rhabdomyosarcoma cells by cytokine-induced killer cells: implications for adoptive immunotherapy after allogeneic stem cell transplantation.
abstract: 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.
  
  
  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 TCRalphabeta 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.
authors.affiliation: University Children's Hospital III, University Children's Hospital III, Department of Hematology/Oncology Department of Hematology/Oncology, Theodor-Stern-Kai 7. selim.kuci@kgu.de
authors.forename: Selim
authors.initials: S
authors.lastname: Kuçi
authors.forename: Eva
authors.initials: E
authors.lastname: Rettinger
authors.forename: Bernhard
authors.initials: B
authors.lastname: Voss
authors.forename: Gerrit
authors.initials: G
authors.lastname: Weber
authors.forename: Miriam
authors.initials: M
authors.lastname: Stais
authors.forename: Hermann
authors.initials: H
authors.lastname: Kreyenberg
authors.forename: Andre
authors.initials: A
authors.lastname: Willasch
authors.forename: Zyrafete
authors.initials: Z
authors.lastname: Kuçi
authors.forename: Ewa
authors.initials: E
authors.lastname: Koscielniak
authors.forename: Stephan
authors.initials: S
authors.lastname: Klöss
authors.forename: Dorothee
authors.initials: D
authors.lastname: von Laer
authors.forename: Thomas
authors.initials: T
authors.lastname: Klingebiel
authors.forename: Peter
authors.initials: P
authors.lastname: Bader
mesh_terms: D055612:Cytokine-Induced Killer Cells / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006801:Humans; D016219:Immunotherapy, Adoptive / Q000379:methods; D012208:Rhabdomyosarcoma / Q000276:immunology* / Q000628:therapy*; D014184:Transplantation, Homologous