Human Cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) are endowed with the ability of establishing lifelong latency in human hosts and reactivating in immunocompromised subjects, including patients suffering from ulcerative colitis (UC). We, therefore, aimed to investigate virus-specific immunity in UC patients. A cohort of 24 UC patients (14 responders and 10 refractory to therapy) and 26 control subjects was prospectively enrolled to undergo virus-specific serology (by ELISA assay) and assessment of both CD4+ and CD8+ virus-specific T-cell response (by interferon-γ enzyme-linked immunospotanalysis). In parallel, mucosal viral load was determined by quantitative real-time PCR and the values were correlated with both clinical and endoscopic indexes of activity. For statistics, the t-test, Mann-Withney test, Fisher's exact test and Spearman rank correlation test were applied; p < 0.05 was considered significant. EBV-specific CD4+ and CD8+ T-cell responses were significantly lower in UC patients compared to controls (p < 0.0001 and p = 0.0006, respectively), whereas no difference was found for HCMV-specific T-cell response. When dividing the UC group according to response to therapy, both responders and refractory UC patients showed a deficient EBV-specific CD4+ T-cell response with respect to controls (p < 0.04 and p = 0.0003, respectively). Moreover, both EBV and HCMV mucosal loads were significantly higher in refractory UC than in responders and controls (p = 0.007 and 0.003; and p = 0.02 and 0.001, respectively), and correlated with activity indexes. Steroid therapy seemed the main risk factor for triggering EBV colitis. Finally, no cases of IgM positivity were found in the study population. An impaired EBV-specific immunity was clearly evident in UC patients, mostly in those refractory to therapy. The ELISPOT assay may serve as new tool for quantifying and monitoring virus-specific T-cell immunity in UC.

1st Department of Internal Medicine Faculty of Medicine Comenius University and University Hospital Bratislava Slovakia

Department of Clinical Surgical Diagnostics and Pediatric Sciences University of Pavia Pavia Italy

Department of Internal Medicine San Matteo Hospital Foundation University of Pavia Pavia Italy

Experimental Research Laboratories Biotechnology Area San Matteo Hospital Foundation Pavia Italy

Gastroenterology Unit Department of Medicine A O U 1 Policlinico G B Rossi University of Verona Piazzale L A Scuro 10 37134 Verona Italy

Molecular Virology Unit Microbiology and Virology Department San Matteo Hospital Foundation Pavia Italy

Nd Department of Surgery Faculty of Medicine Masaryk University and St Anne's University Hospital Pekarska 53 65691 Brno Czech Republic

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