TNF and infection: Unexpectedly, increased large intestinal IFN-γ and TNF concentrations could also be observed in commensal E. coli as compared to uninfected mice (p<0.001 and p<0.01, respectively; Fig 6A and 6B), whereas only colonic TNF was lower 6 days following E. coli versus CCUG 30485 strain infection (p<0.05; Fig 6B).