A control for the day‐to‐day normalization of the flow cytometry γ‐H2AX assay for clinical routine

Background The phosphorylation of histone H2AX (γ‐H2AX) at the DNA double‐strand break (DSB) site is frequently used for quantifying DSBs and may be useful as a biomarker for clinical applications. We have previously reported a flow cytometry‐based quantification of γ‐H2AX for clinical routine. One major challenge, however, is the lack of a control sample for normalization of the day‐to‐day variation of the flow cytometry γ‐H2AX assay. Methods Here, we report development of a mix‐control sample containing peripheral blood mononuclear cells (PBMC) from 10 control individuals, for normalization of day‐to‐day variation of the flow cytometry‐γ‐H2AX assay. Results We showed that control individuals sampled on different days show an average day‐to‐day variation (CV) of 34%, which was reduced to 12% after normalization to the control sample. The normalization allowed detection of radiosensitivity of lymphoblastoid cell lines from ataxia telangiectasia patients, sampled over three days. Conclusion The mix‐control sample, consisting of 10 control individuals’ PBMC, can be used as a control sample to normalize for day‐to‐day variation of the γ‐H2AX assay. The use of this sample will facilitate integration of the γ‐H2AX assay into clinical routine. © 2018 International Clinical Cytometry Society