FIG. 2.

S. flexneri-T84-cell basolateral membrane association induces PMN transepithelial migration. Polarized monolayers of T84 intestinal epithelial cells were either apically or basolaterally exposed to wild-type S. flexneri 2457T (open bars) or a noninvasive plasmid-cured strain BS103 (solid bars) at a density of 80 cell-associated bacteria/epithelial cell. The ability of S. flexneri to induce PMN transepithelial migration was assessed 90 min later (see Materials and Methods). The negative control (−) (gray bar) represents HBSS(+) buffer in the absence of bacteria or a chemotactic stimulus. A positive control was established by using imposed gradients to the chemotactic peptide fMLP (10⁻⁷ M) ([15.12 ± 2.36] × 10⁴ CE). Data are means and SD for four monolayers in a single experiment and are representative of four separate experiments.