Inhibition of mitochondria by CCCP impairs PMN chemotaxis. (A) Freshly isolated primary human PMNs were exposed to a chemotactic gradient using a micropipette loaded with 100 nM fMLP, and migration of cells was recorded under the microscope. The chemotactic behavior of untreated cells and of cells pretreated with 1 µM CCCP with or without 100 µM ATPγS was compared using traces of individual cells (see also Video 1, top). Data shown are representative of results obtained with cells from at least three different healthy individuals. (B) The total length each cell traveled over the observation period was used to calculate migration speed. The effective migration speed was calculated from the Euclidean distance each cell traveled. Cells were considered to migrate in the correct direction when their migration paths did not deviate by more than 60° from a straight line toward the micropipette tip. Cells were isolated from at least three different healthy individuals, and data are expressed as mean ± SD (error bars) of n = 20–40 cells from each donor. Statistical analysis was done with one-way ANOVA; *, P < 0.05.