P701. Cytomegalovirus-specific T-cell response is conserved in IBD patients
R. Caccaro1, A. Saldan2, D. Abate2, M. Martinato1, R. D'Incà1, G. Palù2, G.C. Sturniolo1, 1University of Padova, Department of Surgical Oncological and Gastroenterological Sciences, Padova, Italy, 2University of Padova, Department of Molecular Medicine, Padova, Italy
The role of cytomegalovirus (CMV) infection in patients with inflammatory bowel disease (IBD) is uncertain. IBD patients are an emerging category at risk, because of immunosuppression and the preferential tropism of CMV for inflammation. CMV has been proposed to be responsible for flares and/or resistance to medical treatment; however, it is still unknown whether viral reactivation is related to IBD relapse itself or to the loss of immune-competence during immunosuppressive treatment. CMV-specific T-cell response plays a pivotal role in maintaining viral latency and controlling replication; its evaluation could be used for risk monitoring during immunosuppressive treatment. The aim of this study is to evaluate the CMV-specific T-cell immune response in IBD patients and to explore possible correlations with disease activity and type of treatment.
We included in the study 84 patients: 36 Crohn's disease (CD) and 48 ulcerative colitis (UC). For each patient the CMV serology status has been evaluated and in IgG-positive patients the CMV-specific T-cell response was assessed in peripheral blood (PBMCs), using an IFN-g ELISPOT. Patients were stratified according to disease clinical activity (Harvey Bradshaw Index for CD and Modified Truelove–Witts Severity Index for UC) and according to the therapeutic regimen (immunosuppressives, such as steroids, anti-TNF alpha agents and thiopurines, versus non immunosuppressives, such as 5-aminosalicylates compounds).
Twenty out of 84 patients (24%) were CMV IgG negative and therefore not tested with IFN-g ELISPOT. We observed a significant difference in CMV-specific T-cell response between CD and UC patients (median values: 82 and 128 spots/200000 PBMCs, respectively; p < 0.05). However, no significant differences were observed in CMV-specific cellular immunity with respect to disease activity (remission vs active disease) and type of treatment. The majority of patients (51 out of 64, 80%) displayed moderate-to-high CMV-specific immune response (>20 spots). The 13 patients with low levels of CMV-specific T-cells in the peripheral blood (<20 spots) were all on immunosuppressive therapy.
Despite immunosuppressive therapy, CMV-specific T-cell response is conserved among IgG-positive IBD patients. Low levels of peripheral CMV specific T-cells may expose to viral reactivation, and possibly to flares and general worsening of IBD. The immunological test with IFN-g ELISPOT may be useful in identifying patients at higher risk.