P261 Frequency of B-cell subsets in infliximab-treated paediatric IBD patients
A. Schnell*1, B. Schwarz1, M. Wahlbuhl-Becker1, I. Allabauer1, T. Rechenauer1, G. Siebenlist1, S. Kaspar1, C. Ehrsam1, A. Rückel1, W. Rascher1, A. Hörning1
1Universitätsklinikum Erlangen, Kinder- und Jugendklinik, Erlangen, Germany
The role of B cells in IBD is ambiguous, as B cells may have both pathogenic as well as protective functions in IBD. On the one hand, autoreactive B cells may contribute to mucosal inflammation via secretion of autoantibodies. On the other hand, B cell subsets with regulatory properties like transitional B cells are thought to provide an anti-inflammatory milieu by producing IL10 and TGF-β. The aim of the study was to investigate in a first step frequency patterns of B cell subsets in paediatric IBD patients undergoing a treatment with Infliximab (IFX).
The numerical distributions of transitional, naïve and memory B cells as well as antibody-secreting cells like plasmablasts and plasma cells were assessed at initiation of therapy and in the longitudinal course by FACS multi-colour analysis. The study included 9 children with UC and 13 with CD and 9 age-matched healthy controls. Blood samples were obtained at baseline, before fourth infusion at the end of induction phase and after 6 and 12 months under therapy maintenance. With regard to clinical and biochemical remission, we categorised every patient with a faecal calprotectin level below 100 µg/g or a decrease of <10% of the baseline value after 12 months as responder.
Compared with healthy controls, FACS analysis revealed significantly low percentages of transitional B cells in UC (
The results of our study suggest an involvement of B cells in the pathogenicity of IBD. Especially the findings in UC patients with high frequencies of antigen-experienced memory B cells in contrast to reduced percentages of transitional B cells point towards a disbalance between pro- and anti-inflammatory elements in paediatric IBD. In CD, our findings within all B cell subsets are more ambiguous, suggesting a rather heterogenous B cell spectrum in CD patients.