Comparison of ROS levels in resting and activated primary PBMC versus Jurkat cells. (A) Morphologic properties of primary resting PBMC (left), mitogen-activated PBMC (middle), and Jurkat cells (right) analyzed by flow cytometry (FSC-SSC scatter plots); indicated are the gate areas containing most of the cell populations. (B) A combined FSC-SSC scatter plot of these cell populations. (C) ROS levels (measured with H₂-MTR) in the 3 gate areas corresponding to primary PBMC (resting or mitogen-activated) and Jurkat cells. Results indicated that mitogen-induced activation was associated with increasing levels of ROS and that Jurkat cells exhibited markedly increased ROS levels compared with primary cells.