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P201. Lymphocytes minor subsets mitochondrial enzymes activity in children with IBD under infliximab therapy

L. Kuznetsova1, S. Petrichuk1, I. Samohina1, A. Potapov2, E. Tsimbalova2, M. Venediktova2, 1Scientific Center of Children's Health, Cytochemical laboratory, Moscow, Russian Federation, 2Scientific Center of Children's Health, Gastroenterology department, Moscow, Russian Federation

Background

Lymphocytes are one of the most important participant in the immune mediated inflammation; theirs functioning depends on the energetic supply. Mitochondrial enzymes activity reflects cell energetic process intensity. The succinate dehydrogenase (SDH is both respiratory chain and Krebs cycle enzyme) activity measurement is a widespread method of the cells bioenergetic condition evaluation. The measurement of the SDH activity in the minor peripheral lymphocytes subsets helps in the estimation of the cells immunity parts functioning and opens up a new diagnostic possibility in patients with IBD.

Methods

We studied 44 children with Crohn's disease (CD) and 26 patients with ulcerative colitis (UC) at the age from 10 to 18 years, who were under infliximab therapy for a long period. We investigated lymphocytes SDH activity by quantitative citochemical method, based on the n-nitrotetrazolium violet ability to form insoluble formazan granules during enzymic reduction with a help of flow cytometer Beckman Coulter FC500 (USA) Clinical effect of the therapy was assessed using pediatric Crohn's disease activity index (PCDIA) and pediatric ulcerative colitis activity index (PUCAI).

Results

We showed that children with CD and UC had statistically significant decrease of the B-cells number and their SDH activity and aggravated with the disease duration increase. B1-cells subset was less in patients with UC and CD compared to healthy children – median 12.5±0.3% versus 30.9±2.6% of B-cells, on the contrary SDH activity was higher in patients with UC and CD (153.6±6.4 relative unit (r.u.) than in healthy children (108.3±3.9r.u.). Gradual intense growth of the SDH activity and B1-cells number was observed in patients with nonsustained effect of infliximab. T-cells immunity analysis showed that activated T-helpers predominated over regulatory T-cells population in children with nonsustained effect of infliximab. Activated T-helpers SDH activity was higher in patient with CD and UC than in healthy children. Statistical analysis by multiple stepwise regression method showed that the lower the regulatory T-cells activity, the worse the infliximab efficacy prognosis (R2=0.81).

Conclusion

Thus, our data suggest that the assessment of minor lymphocytes subsets SDH activity has diagnostic value and can be recommended as additional criterion in the follow-up of children with inflammatory bowel disease, especially receiving anti-cytokine therapy.