PMA dose response curve. The reaction mixture contained 2 × 10⁶ Jurkat LTR_luc, either 10⁶ or 10⁷ neutrophils/mL and PMA at the concentrations indicated in RPMI at a final volume of 2.0 mL. The results are the mean ± SEM of four experiments. The y-axis was broken to allow for an increased scale in the lower range to illustrate the inhibitory effect of high neutrophil concentrations.