γH2AX in non-irradiated (control) and 2 Gy irradiated cells that were co-stained with CD3 for labeling T cells (A–D) and CD14 for labeling monocytes (E). (A) PBMCs after Ficoll density centrifugation. (B) Whole blood from buffy coat with erythrolysis. (C) Whole blood from buffy coat without erythrolysis. (D) Drop of blood from fingertip. (E) Monocytes from drop of blood.