CD4+CD25+ regulatory T cells have divergent effects on intestinal inflammation in IL-10 gene-deficient mice.

The regulatory effect of murine CD4+CD25+ T-cells in vivo appears to be dependent on the secretion of IL-10. The lack of IL-10 in the IL-10 gene-deficient mouse has a profoundly negative effect on the mouse's regulation of the response to intestinal bacteria, resulting in severe enterocolitis. We investigated the effect of neonatal injection with wild-type CD4+CD25+ T-cells on the intestinal immune response in IL-10 gene-deficient mice. At the time of analysis, 8-15 weeks later, all mice demonstrated an increased, antigen-stimulated systemic response. However, the intestinal response was divergent with about half of the mice developing an intestinal inflammation with a high injury score, the other half demonstrating a remarkable reduction in injury score with a marked decrease in intestinal IFNgamma release. Our data demonstrate that CD4+CD25+ T-cells can be activated in IL-10 gene-deficient mice and that this stimulation under stringent conditions has the potential to reduce intestinal inflammation.