title: Effects of ultrasound on apoptosis induced by anti-CD20 antibody in CD20-positive B lymphoma cells.
abstract: OBJECTIVE
  The present study was conducted to examine the thermal and non-thermal effects of ultrasound on apoptosis induced by anti-CD20 monoclonal antibody (rituximab).
  
  
  METHODS
  SU-DHL-4 cells, a CD20-positive cell line derived from B cell lymphomas with a BCL2 gene rearrangement, were exposed to continuous 1 MHz ultrasound for therapeutic use under an air- or CO(2)-saturated condition to control cavitation. Early apoptosis (EA) and secondary necrosis (SN) were examined by flow cytometry. Cavitation was determined by detecting the hydroxyl radicals derived from pyrolysis of water molecules using electron paramagnetic resonance-spin trapping. To assess thermal effects, cells were treated in a temperature-controlled water bath.
  
  
  RESULTS
  There was a significant additive increase in EA and EA+SN observed in cells treated with rituximab combined with heat at 42 degrees C or non-thermal ultrasound at 0.5 W/cm(2) under an air-saturated condition, where heat or ultrasound induced some cell death. A significant synergistic increase in EA and EA+SN was observed in cells treated with rituximab and ultrasound at 2.5 W/cm(2) under CO(2)-saturated conditions, where inertial cavitations were completely suppressed. No enhancement was observed at a temperature less than 40 degrees C or ultrasound at 0.5 W/cm(2) under CO(2)-saturated conditions.
  
  
  CONCLUSIONS
  These results suggest that the immuno-therapeutic application of ultrasound at relatively high-intensities combined with rituximab thus produces synergistic effects under conditions where the non-thermal and non-cavitational effects are predominant.
authors.affiliation: Department of General Medicine, Nara Medical University School of Medicine, Kashihara, Nara, Japan. Electronic address: ddanno@naramed-u.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Danno
authors.affiliation: Department of General Medicine, Nara Medical University School of Medicine, Kashihara, Nara, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kanno
authors.affiliation: Department of General Medicine, Nara Medical University School of Medicine, Kashihara, Nara, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Fujimoto
authors.affiliation: Department of Anatomy, Fukuoka University School of Medicine, Fukuoka, Japan.
authors.forename: Loreto B
authors.initials: LB
authors.lastname: Feril
authors.affiliation: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Department of General Medicine, Nara Medical University School of Medicine, Kashihara, Nara, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20 / Q000276:immunology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006358:Hot Temperature; D006801:Humans; D016393:Lymphoma, B-Cell / Q000276:immunology / Q000473:pathology*; D000069283:Rituximab; D014465:Ultrasonics
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000970:Antineoplastic Agents; D005609:Free Radicals; D000069283:Rituximab