. The effect of the microorganisms upon IEC growth and proliferation, as well as
on cytokine production, was determined. A high dependence on both the IEC line used and
the strain tested was observed. None of the strains modified the growth or proliferation of
HT29-cells but some affected that of Caco2. The presence of the bacteria did not affect cytokine
production by Caco2-cells, but some strains modulated the cytokine production by
HT29-cells. IL-1b and IL-6 production was reduced by all bacteria tested and most, except
Bifidobacterium longum 1/10, Bifidobacterium breve 99/E8 and Propionibacterium freudenreichii
PJS, reduced the production of IL-8. Lactococcus lactis ARH4 was the bacteria stimulating
the highest production of TNFa, whilst Pr. freudenreichii PJS significantly increased IL-10 production
and Bifidobacterium animalis Bb12 reducing it. This work evidences that the cellular
model used to test bacterial host-cells interaction has a great impact on the results
obtained.