title: Flow cytometric immunofluorescence assay for quantification of cyclobutyldithymine dimers in separate phases of the cell cycle.
abstract: Quantitative immunofluorescence assays for the measurement of cyclobutyldithymine dimers (T <> T) based on computer-assisted immunofluorescence microscopy have recently been described. Here we present a modified assay for T <> T based on flow cytometry. This method has the advantage that T <> T can be quantified in separate phases of the cell cycle by the fluorescent counterstaining of nuclear DNA and subsequent selection on DNA content. The H3 monoclonal antibody directed at T <> T binds to partially denatured DNA in situ. The antibody is labeled with fluorescein isothiocyanate (FITC) and DNA is stained with the intercalating dye 7-amino-actinomycin D. FITC fluorescence increases linearly with dose of UV-C radiation (up to 45 J/m2) of cultured human fibroblasts. A linear fluorescence-dose relationship was also found for epidermal cells of SKH:HR1 hairless mice after in vivo irradiation with UV-B (FS40 sunlamp, up to 3750 J/m2). This technique allows a quick assessment of UV damage levels in 10,000s of cells and makes immunofluorescence of DNA damage more accessible to other research groups.
authors.affiliation: Institute of Dermatology, Academic Hospital Utrecht, The Netherlands.
authors.forename: R J
authors.initials: RJ
authors.lastname: Berg
authors.forename: F R
authors.initials: FR
authors.lastname: de Gruijl
authors.forename: L
authors.initials: L
authors.lastname: Roza
authors.forename: J C
authors.initials: JC
authors.lastname: van der Leun
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D008812:Mice, Hairless; D011740:Pyrimidine Dimers / Q000032:analysis*; D012867:Skin / Q000166:cytology / Q000528:radiation effects; D013941:Thymine / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D011740:Pyrimidine Dimers; C059224:cyclobutyldithymidine dimers; D013941:Thymine