title: Short-term culture and gammaH2AX flow cytometry determine differences in individual radiosensitivity in human peripheral T lymphocytes.
abstract: Histone H2AX, a subfamily of histone H2A, is phosphorylated and forms proteinaceous repair foci at the sites of DNA double-strand breaks in response to genotoxic insults, such as ionizing radiation. This process is believed to play a key role in the repair of DNA damage. In this study, we established a flow cytometry (FCM) system for measuring radiation-induced phosphorylated histone H2AX (gammaH2AX) in cultured human T lymphocytes to evaluate individual radiation sensitivity in vitro. Irradiation of short-term ( approximately 7 days) cultured T lymphocytes exhibited significant interindividual, but not interexperimental, differences in the cellular content of gammaH2AX 6 hr after 4 Gy of X-irradiation in three independent experiments using peripheral blood lymphocytes from six healthy donors. However, these differences were not as marked in uncultured lymphocytes, or lymphocytes that were cultured for a prolonged period ( approximately 13 days). The variation of gammaH2AX focus formation in lymphocytes of individuals was reproducible, with differences reaching about 1.5-fold following 7 days of culture. Therefore, the FCM-based gammaH2AX measurement appeared to reflect both the temporal course and the amount of DNA damage within the irradiated lymphocytes. Further, we confirmed that the differences in residual lymphocyte subsets were not involved in individual radiosensitivity. These results suggest that the FCM-based gammaH2AX assay using cultured T lymphocytes might be useful for the rapid and reliable assessment of individual radiation sensitivity involved in DNA damage repair.
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Kanya
authors.initials: K
authors.lastname: Hamasaki
authors.forename: Kazue
authors.initials: K
authors.lastname: Imai
authors.forename: Kei
authors.initials: K
authors.lastname: Nakachi
authors.forename: Norio
authors.initials: N
authors.lastname: Takahashi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kodama
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Kusunoki
mesh_terms: D000328:Adult; D017252:CD3 Complex / Q000032:analysis; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D016193:G1 Phase / Q000528:radiation effects; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D016131:Lymphocyte Subsets / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D011836:Radiation Tolerance; D017452:Receptors, IgG / Q000032:analysis; D016192:Resting Phase, Cell Cycle / Q000528:radiation effects; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors; D014965:X-Rays
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D017452:Receptors, IgG; D017493:Leukocyte Common Antigens