Uropathogenic strains of Escherichia coli bearing mannose-sensitive (type 1) fimbriae promote a unique pattern of degranulation from human polymorphonuclear leukocytes (PMN). Significant quantities of the primary (10) and tertiary (30) granule markers, neutral protease-myeloperoxidase and N-acetyl-o-D-glucosaminidase, respectively, were released by PMN in a dose-and time-dependent manner when stimulated by these defined bacterial strains. Organisms bearing mannose-resistant (P) fimbriae promoted release of only the secondary (2°) granule marker, vitamin B12-binding protein. When this pattern of degranulation was compared to that produced by PMN in response to a variety of soluble and particulate stimuli, only the calcium ionophore A23187 similarly triggered 1°and 30 granule marker release. All the other stimuli tested-zymosan, serum-treated and unopsonized; n-formylmethionyl-leucyl-phenylalanine; and phorbol myristate acetatepromoted release of only the 2°granule marker. These results demonstrate selectivity of PMN degranulation in response to a number of transmembrane signals. In addition, the capacity of E. coli to promote PMN degranulation is dependent on its phenotypic fimbrial expression, a surface characteristic which correlates significantly with its relative surface hydrophobicity as measured by binding to octyl Sepharose. Those bacteria demonstrating the greatest hydrophobicity were capable of triggering discharge of all three granule marker proteins. Thus, the mannose-sensitive fimbriae of uropathogenic E. coli may contribute significantly to their potential pathophysiologic role in renal scarring.
Luminol-dependent chemiluminescence and thiol group oxidation of glutathione and human serum albumin were measured in order to demonstrate whether the inhibition of polymorphonuclear leukocyte chemiluminescence by albumin was attributable to thiol group oxidation. We have shown that: 1. thiol groups on glutathione and albumin are oxidized by PMNL stimulated by soluble and phagocytic stimuli; 2. thiol group oxidation in albumin and glutathione did not correlate with the inhibitory effects of these substances on luminol-dependent chemiluminescence with respect to time course, magnitude, effects of known scavengers or extracellular activity. It was therefore concluded that thiol group oxidation was not the cause of albumin inhibition of luminol-dependent chemiluminescence; 3. a metastable oxidant was identified after PMNL activation which was capable of oxidizing thiol groups but unable to elicit chemiluminescence from luminol.
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