Blood for γH2AX staining.
(a) PBMCs obtained by Ficoll gradient centrifugation. 5–10 ml peripheral blood were usually collected in heparinized tubes, which is layered onto a Ficoll gradient. Following centrifugation, the layer containing PBMCs was harvested, washed four times, concentrated by centrifugation and fixed onto glass slides. (b) A drop of blood is taken up in a heparinized glass micro-hematocrit capillary tube and spread onto one or several glass slides.