title: Dose response and repair kinetics of gamma-H2AX foci induced by in vitro irradiation of whole blood and T-lymphocytes with X- and gamma-radiation.
abstract: OBJECTIVE
  Dose response and repair kinetics of phosphorylated histone H2A isoform X (gamma-H2AX) foci in T-lymphocytes were investigated in the low-dose range after in vitro irradiation of whole blood and T-lymphocytes with 100 kVp X-rays and (60)Co gamma-rays.
  
  
  METHODS
  Whole blood or isolated T-lymphocytes were irradiated in vitro and gamma-H2AX foci were scored. Dose response was determined in the 0-500 mGy dose range. Foci kinetics were studied at doses of 5 and 200 mGy up to 24 h post-irradiation.
  
  
  RESULTS
  After X-irradiation, the dose response for whole blood shows a biphasic behaviour with a low-dose hypersensitivity, which is less pronounced for isolated T-lymphocytes. In contrast, gamma-radiation shows a linear dose response for both irradiation conditions. Concerning repair kinetics, delayed repair was found after X-ray whole blood irradiation (5 and 200 mGy) with 40% of the foci persisting 24 h post-irradiation. This number of foci is reduced to 10% after irradiation of isolated T-lymphocytes with 200 mGy X-rays. On the contrary, gamma-H2AX foci are reduced to background levels 24 h post-irradiation with 200 mGy (60)Co gamma-rays.
  
  
  CONCLUSIONS
  gamma-H2AX foci response and repair kinetics depend on irradiation conditions and radiation quality, possibly linked to Bystander response.
authors.affiliation: Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Gent, Belgium. Laurence.Beels@UGent.be
authors.forename: Laurence
authors.initials: L
authors.lastname: Beels
authors.forename: Joke
authors.initials: J
authors.lastname: Werbrouck
authors.forename: Hubert
authors.initials: H
authors.lastname: Thierens
mesh_terms: D000328:Adult; D001773:Blood Cells / Q000737:chemistry / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D006657:Histones / Q000032:analysis*; D006801:Humans; D008297:Male; D013601:T-Lymphocytes / Q000737:chemistry / Q000528:radiation effects*; D014965:X-Rays; D055815:Young Adult
chemical_list: C468783:H2AX protein, human; D006657:Histones