Phosphorylated Histone 2AX Foci Determination in Capillary Blood Mononuclear Cells

Background: One of the most severe variants of DNA lesions is the DNA double-strand break (DSB). Generally, non-physiological DSBs occur as a result of ionizing radiation, oxidative or mechanical stress and chemical effects. DSBs can be detected by phosphorylated histone 2AX (γH2AX) foci analysis using indirect immunofluorescence assay (IFA). Peripheral blood mononuclear cells (PBMCs) obtained by venipuncture and density gradient centrifugation have mainly been used for DSB assessment applying IFA but capillary blood mononuclear cells (CBMCs) could be an alternative facilitating DSB analysis. Methods: CBMCs and PBMCs were isolated from capillary and venous blood of ten human volunteers. Nuclear characteristics and DSBs induced by etoposide were determined by IFA using an automated microscopy interpretation system for DNA damage assessment. Results: The number of isolated PBMCs and CBMCs, their nuclear characteristics as well as the number and characteristics of etoposide-induced DSBs were not significantly different in capillary and venous cells (P>0.05). Conclusions: CBMCs isolated from capillary finger stick blood can be used for DSB analysis by γH2AX foci assessment instead of PBMCs obtained by venipuncture. The use of CBMCs could enhance the implementation of γH2AX as a biomarker for individual diagnostics in precision medicine.