['FTY720 is an immunosuppressive molecule licensed for the treatment of chronic relapsing multiple sclerosis (MS). It attenuates the adaptive immune response by sequestering T cells within secondary lymphoid organs via its action as functional antagonist of sphingosine-1-phasphate. To date it is unknown whether FTY-induced lymphopenia puts MS patients at increased risk for severe forms of postoperative infectious complications such as abdominal sepsis.', 'To determine the effect of FTY720-induced lymphopenia on survival to sepsis secondary to postoperative intraabdominal infections in a murine model of polymicrobial sepsis.', 'Detailed analysis of cellular dynamics in secondary lymphoid organs and of cytokine profiles was performed in FTY720-treated or placebo-treated C57BL/6 mice after induction of Colon ascendens stent peritonitis (CASP). Furthermore, survival analysis was performed in FTY720-treated and placebo-treated animals in severe CASP. Fifty per cent of each group were treated with broad spectrum antibiotics.', 'FTY720 treatment resulted in remodelling of cell populations present in the peripheral blood, the peritoneal cavity and the spleen after CASP induction. Both lymphoid and myeloid cell lines were affected. However, survival in lymphopenic FTY720-treated animals was similar to placebo-treated mice following CASP. Antibiotic treatment increases survival in untreated as well as FTY720-treated animals to a similar extent.'] Does fTY720-Induced Lymphopenia Aggravate Mortality in a Murine Model of Polymicrobial Abdominal Sepsis?