Figure 2
Intestinal epithelial cells secrete interleukin (IL)-8 differentially in response to various bacteria. Confluent HT-29 cells were treated with Salmonella typhimurium (1 × 107 colony-forming units (CFU)/ml), flagellin (0.5 μg/ml), Clostridium difficile (1 × 107 CFU/ml), an equal volume of their cell-free culture supernatants, Mycobacterium paratuberculosis (1 × 108CFU/ml), M. smegmatis (1 × 108 CFU/ml), Bifidobacterium infantis (1 × 107 CFU/ml), or Lactobacillus salivarius (1 × 107 CFU/ml). IL-8 protein levels in cell culture supernatants were measured after 6 hr, 12 hr, or 24 hr as specified by enzyme-linked immunosorbent assay. The data are expressed as pg/ml IL-8 and represent the mean ± standard error (n = 7 independent experiments). *P < 0.05 relative to untreated cells.