Good day, I would like to ask a technical question about my samples. In order to analyze DNA damage, I immunostain the PBMC cells with 1:500 ratio primary and secondary antibodies to get the foci number. One foci means one DNA double strand break.

However, after staining, non-irradiated cell also show considerable amount of radiation damage, each cell has 15 to 25 foci/DSBs even before irradiation of the cells. Is the concentration of antibodies too high? Or is it related to residual DNA damage? However, patients had never undergo a computed tomography before.

Would appreciate any help on this subject.