Phospholipase D and priming of the respiratory burst by H(2)O(2) in NR8383 alveolar macrophages.

Previous investigation showed that preincubation within a range of nontoxic H2O2 concentrations enhanced subsequently stimulated superoxide production by rat alveolar macrophages in response to various stimuli. In the present study, the NR8383 rat alveolar macrophage cell line was used to further investigate the priming effect of H2O2. Using nitroblue tetrazolium, which formed an insoluble formazan when reduced by superoxide, modulation of the respiratory burst was visualized in a cell population exposed to a concentration gradient of H2O2 before stimulation. This model system illustrates how H2O2 may constitute a signaling molecule for a feed-forward regulation of the respiratory burst during inflammation. n-Butanol, which allows consumption of phosphatidic acid by the transphosphatidylation reaction, and propanolol, which inhibits phosphatidic acid phosphohydrolase, were used to investigate the possible involvement of phospholipase D in this phenomenon. These two agents were found to inhibit the basal a...