Fig. (5) IL-8 concentrations in Caco-2 (A) and T84 (B) cell culture supernatants at 3, 24 or 48 h after infection with aEPEC or tEPEC strains or in the absence of infection. Experiments were performed in triplicates at least three times. Error bars indicate standard deviation. (A) aEPEC 1711-4 stimulated IL-8 levels at least three fold those of aEPEC 3991-1 or tEPEC E2348/69, in all periods tested. These differences were statistically significant (P ≤ 0.001). (B) - IL-8 levels induced by aEPEC 1711-4 at 3, 24 and 48 h after infection were significantly higher than those induced by the other strains (P = 0.001).