Intracellular ROS and cytokine production in aged neutrophils. (A) Representative microscopy images illustrating mitochondrial/nuclear and cytosolic ROS generation in unstimulated and LPS-stimulated neutrophils (bars represent 5 µm). Using multichannel flow cytometry, intracellular production of ROS (A) and cytokines (B) was quantitatively analyzed in aged and nonaged neutrophils isolated from the peripheral blood of WT mice as detailed in “Methods.” Quantitative data for neutrophils undergoing exposure to PBS (unstimulated) or LPS are shown. Mean ± SEM for n = 4-6. IFN, interferon; TNF, tumor necrosis factor.