Extracellular release of reactive oxygen species from human neutrophils upon interaction with Escherichia coli strains causing renal scarring.

The production of reactive oxygen metabolites by neutrophils plays a key role in the host defense against invading microorganisms and in tissue damage resulting from infection. In the present study we measured the ability of different uropathogenic Escherichia coli strains to induce generation of oxygen metabolites upon interaction with human neutrophils. The strains were selected to represent two groups of patients with recurrent episodes of acute pyelonephritis: one with renal scars (12 strains) and one without renal scarring (11 strains). The majority of strains (from both groups) induced a pronounced neutrophil respiratory burst activity. When the intracellular and extracellular oxidative responses were measured separately, it was found that the response induced by nonscarring strains was primarily of intracellular (intraphagosomal) origin, whereas a proportionally larger fraction of the response induced by the scarring strains was extracellular. Since reactive oxygen products are toxic to the renal tissue, this release can be of importance in the development of renal scars.