title: In vitro effects of low-level laser irradiation at 660 nm on peripheral blood lymphocytes.
abstract: OBJECTIVE
  The effects of low-level laser light irradiation are still highly contested, and the mechanisms of its action still unclear. This study was conducted to test the effects of low-level laser irradiation at 660 nm on human lymphocytes and to investigate the possible mechanisms by which these effects are produced.
  
  
  METHODS
  Whole blood obtained by phlebotomy was irradiated at 660 nm by using energy fluences between 0 and 5.0 J/cm(2). The lymphocytes were isolated after irradiation of the whole blood. For the control experiment, the lymphocytes were first isolated and then irradiated at the same wavelength and energy fluence for comparison. The proliferation of lymphocytes and the formation of free radicals and lipid peroxides were monitored. Hemoglobin was also irradiated in a cell-free environment to test for the production of lipid peroxides.
  
  
  RESULTS
  Lymphocyte proliferation was significantly higher (P<0.05) as expressed by a Stimulation Index in samples irradiated in the presence of whole blood compared with lymphocytes irradiated after isolation from whole blood. Free radical and lipid peroxide production also increased significantly when samples were irradiated in the presence of red blood cells.
  
  
  CONCLUSIONS
  The present study supports the hypothesis that one mechanism for the photobiostimulation effect after irradiation at 660 nm is the reaction of light with hemoglobin, resulting in oxygen radical production.
authors.affiliation: The Laser Center and Department of Surgery, Rochester General Hospital, Rochester, New York 14621, USA. istvan.stadler@viahealth.org
authors.forename: I
authors.initials: I
authors.lastname: Stadler
authors.forename: R
authors.initials: R
authors.lastname: Evans
authors.forename: B
authors.initials: B
authors.lastname: Kolb
authors.forename: J O
authors.initials: JO
authors.lastname: Naim
authors.forename: V
authors.initials: V
authors.lastname: Narayan
authors.forename: N
authors.initials: N
authors.lastname: Buehner
authors.forename: R J
authors.initials: RJ
authors.lastname: Lanzafame
mesh_terms: D001769:Blood / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004912:Erythrocytes / Q000528:radiation effects; D006454:Hemoglobins / Q000528:radiation effects; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D008054:Lipid Peroxides / Q000096:biosynthesis; D018655:Lymphocyte Count; D008214:Lymphocytes / Q000528:radiation effects*; D010789:Phototherapy / Q000379:methods*; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase / Q000096:biosynthesis; D014945:Wound Healing; D014947:Wounds and Injuries / Q000188:drug therapy*
chemical_list: D006454:Hemoglobins; D008054:Lipid Peroxides; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase