FIG. 3.
Chemokine induction by the human monocytic cell line 28SC. (A) Induction of IL-6 and IL-8 by whole cells of C. jejuni. Live C. jejuni 81-176 or the cdt mutant DS105 was added to 28SC cells at an MOI of 100:1 as described previously, and IL-6 and IL-8 secretion levels were determined by enzyme-linked immunosorbent assay (ELISA) after 24 h of incubation. The P values for IL-6 and IL-8 secretion comparing the wild type to DS105 were 0.18 and 0.09, respectively. (B) Induction of IL-6 and IL-8 by membrane fractions from 81-176 or DS105. Bacterial membrane protein (2 μg) was added to each ml of 28SC culture maintained at 2.5 × 105 to 1.0 × 106 cells/ml. At 24 h, the culture supernatants were collected and assayed for IL-6 and IL-8 by ELISA. The P values for IL-6 and IL-8 secretion comparing the wild type to DS105 were 0.74 and 0.65, respectively. P values were calculated assuming unequal variance. Black solid, uninoculated control; grey solid, 81-176 inoculated; white, DS105 inoculated. The black bars are barely visible because of the low background level. The data represent the means and standard deviations of three to nine independent experiments.