Tumor Necrosis Factor Primes Neutrophils by Shortening the Lag Period of the Respiratory Burst

Pretreatment of neutrophils (PMNs) with low-dose tumor necrosis factor (TNF) enhances their capacity to produce oxidant radicals after stimulation with a variety of agents (‘priming’). We used a continuous cytochrome C assay to Investigate the superoxide production lay human PMNs primed with TNF and subsequently stimulated with phorbol my-ristate acetate (PMA). There was no difference in the maximum rate of superoxide production by primedand unprimed PMNs stimulated with either high (2 × 10 −6M) or low levels of PMA (2 × 10−8M). Following stimulation with high levels of PMA, primed PMNs demonstrated a significantly shorter lag period than unprimed cells (103.3 ± 14.4 vs. 142.1 ± 21.7 seconds) and larger amounts of superoxide generated in the intervals between 100 seconds (3.1 ± 0.5 vs. 1.7 ± 0.3 nmol/106 PMNs) and 300 seconds (14.9 ± 1.2 vs. 12.2 ± 1.1). Primed cells stimulated with low levels of PMA (2 × 10−8M) displayed a significantly shorter lag period (1225.8 ± 96.8 vs. 1573.8 ± 74.3 seconds) and a greater production of superoxide between 1300 seconds (5.4 ± 0.9 vs. 3.0 ± 0.4 nmol/106 PMNs) and 1900 seconds (25.7 ± 4.3 vs. 14.9 ± 2.4) than unprimed cells. These results indicate that priming of PMNs with TNF increases superoxide production during the early phase of the respiratory burst through a shortening of the post-stimulation lag period.