5th Annual BMRP Investigator Meeting - Abstract

CD4+CD25+ T Regulatory Cells in IBD

Kerstin Kapp^b, Jochen Maul, Arlett Wenzel and Rainer Duchmann^a

Medizinische Klinik I, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin (Germany)

CD4+CD25+ regulatory T cells (Treg) are potent suppressors of immune responses and a dysbalance between regulatory and effector T cells is thought to play an important role in the pathogenesis of chronic inflammatory diseases. Since previous results from our group showed a numeric deficit of Treg in active IBD, we now determined whether differences in the frequency of Treg or Treg subsets in peripheral blood of IBD patients can serve as a subclinical marker of disease activity. In addition, we investigated the possibility that Treg from IBD patients have normal suppressive capacity for immune responses to allogeneic antigens but not to bacterial antigens.

We established a combined staining of FOXP3 and CD25, which allows a more precise quantification of Treg by flow cytometry compared to gating on CD4+CD25high cells. Longitudinal analyses in our extended database of IBD patients identify several individuals with decreased frequency of Treg in active disease and increased frequency of Treg in remission, but this is not a consistent trait. Investigating Treg subtypes we could identify subsets with different homing potential. Treg expressing the skin homing marker CLA were more frequent compared to gut homing Treg which express integrin b7. Expression, however, was not significantly different between healthy donors and IBD patients and it was independent from IBD activity.

There is good evidence that bacterial antigens from the intestinal flora drive IBD. We have now established an antigen specific assay for the assessment of Treg function and are currently investigating the suppressive function of Treg in a system driven by selected bacterial antigens.

^aPrincipal Investigator; ^bCo-Investigator and Presenter