TY - JOUR
T1 - Variation in the measurement of DNA damage by comet assay measured by the ECVAG{dagger} inter-laboratory validation trial
AU - Forchhammer, Lykke
AU - Johansson, Clara
AU - Loft, Steffen
AU - Möller, Lennart
AU - Godschalk, Roger W L
AU - Langie, Sabine A S
AU - Jones, George D D
AU - Kwok, Rachel W L
AU - Collins, Andrew R
AU - Azqueta, Amaya
AU - Phillips, David H
AU - Sozeri, Osman
AU - Stepnik, Maciej
AU - Palus, Jadwiga
AU - Vogel, Ulla
AU - Wallin, Håkan
AU - Routledge, Michael N
AU - Handforth, Catherine
AU - Allione, Alessandra
AU - Matullo, Giuseppe
AU - Teixeira, João Paulo
AU - Costa, Solange
AU - Riso, Patrizia
AU - Porrini, Marisa
AU - Møller, Peter
PY - 2010/3
Y1 - 2010/3
N2 - The comet assay has become a popular method for the assessment of DNA damage in biomonitoring studies and genetic toxicology. However, few studies have addressed the issue of the noted inter-laboratory variability of DNA damage measured by the comet assay. In this study, 12 laboratories analysed the level of DNA damage in monocyte-derived THP-1 cells by either visual classification or computer-aided image analysis of pre-made slides, coded cryopreserved samples of cells and reference standard cells (calibration curve samples). The reference standard samples were irradiated with ionizing radiation (0-10 Gy) and used to construct a calibration curve to calculate the number of lesions per 10 6 base pair. All laboratories detected dose-response relationships in the coded samples irradiated with ionizing radiation (1.5-7 Gy), but there were overt differences in the level of DNA damage reported by the different laboratories as evidenced by an inter-laboratory coefficient of variation (CV) of 47%. Adjustment of the primary comet assay end points by a calibration curve prepared in each laboratory reduced the CV to 28%, a statistically significant reduction (P < 0.05, Levene's test). A large fraction of the inter-laboratory variation originated from differences in image analysis, whereas the intra-laboratory variation was considerably smaller than the variation between laboratories. In summary, adjustment of primary comet assay results by reference standards reduces inter-laboratory variation in the level of DNA damage measured by the alkaline version of the comet assay.
AB - The comet assay has become a popular method for the assessment of DNA damage in biomonitoring studies and genetic toxicology. However, few studies have addressed the issue of the noted inter-laboratory variability of DNA damage measured by the comet assay. In this study, 12 laboratories analysed the level of DNA damage in monocyte-derived THP-1 cells by either visual classification or computer-aided image analysis of pre-made slides, coded cryopreserved samples of cells and reference standard cells (calibration curve samples). The reference standard samples were irradiated with ionizing radiation (0-10 Gy) and used to construct a calibration curve to calculate the number of lesions per 10 6 base pair. All laboratories detected dose-response relationships in the coded samples irradiated with ionizing radiation (1.5-7 Gy), but there were overt differences in the level of DNA damage reported by the different laboratories as evidenced by an inter-laboratory coefficient of variation (CV) of 47%. Adjustment of the primary comet assay end points by a calibration curve prepared in each laboratory reduced the CV to 28%, a statistically significant reduction (P < 0.05, Levene's test). A large fraction of the inter-laboratory variation originated from differences in image analysis, whereas the intra-laboratory variation was considerably smaller than the variation between laboratories. In summary, adjustment of primary comet assay results by reference standards reduces inter-laboratory variation in the level of DNA damage measured by the alkaline version of the comet assay.
U2 - 10.1093/mutage/gep048
DO - 10.1093/mutage/gep048
M3 - Journal article
C2 - 19910383
SN - 0267-8357
VL - 25
SP - 113
EP - 123
JO - Mutagenesis
JF - Mutagenesis
IS - 2
ER -