| Abstract: | We compared the degree to which Escherichia coli phase variants which do (T1P+ E. coli) or do not (T1P- E. coli) express type 1 pili (T1P) stimulate human polymorphonuclear leukocyte (PMN) oxidative activity. Unopsonized T1P+ E. coli stimulated the release of 0.20 to 0.24 nmol of H2O2 per 10(6) PMN per min and the consumption of 1.4 to 4.0 nmol of O2 per 10(6) PMN per min; no measurable PMN oxidative activity was stimulated by unopsonized T1P- E. coli. In the presence of serum opsonins, T1P+ E. coli stimulated the release of 1.12 to 1.16 nmol of H2O2 per 10(6) PMN per min and the consumption of 5.0 to 6.0 nmol of O2 per 10(6) PMN per min, whereas T1P- E. coli stimulated the release of 0.42 to 0.43 nmol of H2O2 per 10(6) PMN per min and the consumption of 0.6 to 2.0 nmol of O2 per 10(6) PMN per min. Although unaggregated T1P did not stimulate PMN, latex beads coated with T1P (T1P-latex) stimulated alpha-methylmannoside-inhibitable, opsonin-independent PMN oxidative activity. The activity stimulated by either T1P+ E. coli or T1P-latex was susceptible to inhibition by cytochalasin B. Latex particles coated with bovine serum albumin or mannose-resistant pili did not stimulate PMN. These data indicate that T1P+ E. coli stimulate PMN oxidative metabolism more effectively than do T1P- E. coli and that a similar PMN oxidative response follows cellular stimulation by either unopsonized T1P+ or opsonized T1P- E. coli. Furthermore, T1P-latex faithfully mimics the ability of T1P+ E. coli to stimulate PMN oxidative metabolism. Such particles may be useful in further analyses of cellular responses to T1P+ E. coli. |
