Inflammatory bowel disease (IBD) is associated with a higher prevalence of opportunistic infections. Epstein-Barr virus (EBV) is a ubiquitous virus related to several malignancies, namely lymphoma; its prevalence in patients with IBD and its relation with different therapeutic regimens are not well studied. Patients followed in our IBD outpatient clinic were consecutively enrolled for participation in a prospective study, and healthy volunteers were recruited as controls. EBV DNA was measured at least 1 time in each patient. Three hundred and seventy-nine individuals were enrolled in the study (93 treated with 5-aminosalicylates, 91 with azathioprine, 70 with infliximab, 43 with combined treatment with infliximab and azathioprine, and 82 controls). More than 90% of the patients had previous EBV exposure. EBV DNA was found in 132 samples (35%); its prevalence was significantly higher in every group of patients with IBD, comparing to controls. Among patients with IBD, infliximab with or without azathioprine was related to higher prevalence of EBV comparing to azathioprine alone or 5-aminosalicylates (P < 0.05). Age above 60 years was related to EBV DNA positivity with a specificity of 92%. Concerning treated groups, ulcerative colitis was the only risk factor identified for high levels of EBV DNA (>1000 and 2500 copies per milliliter). No relationship was found between EBV and C-reactive protein. IBD is a risk factor for the presence of EBV DNA in blood, particularly in older patients and in those taking infliximab. C-reactive protein was not related to EBV DNA prevalence.

Summary: Crohn's disease (CD) has been correlated with altered macrophage response to microorganisms. Considering the efficacy of infliximab treatment on CD remission, we investigated infliximab effects on circulating monocyte subsets and on macrophage cytokine response to bacteria. Human peripheral blood monocyte-derived macrophages were obtained from CD patients, treated or not with infliximab. Macrophages were infected with Escherichia coli, Enterococcus faecalis, Mycobacterium avium subsp. paratuberculosis (MAP) or M. avium subsp avium, and cytokine levels [tumour necrosis factor (TNF) and interleukin (IL)-10] were evaluated at different time-points. To evaluate infliximab-dependent effects on monocyte subsets, we studied CD14 and CD16 expression by peripheral blood monocytes before and after different infliximab administrations. We also investigated TNF secretion by macrophages obtained from CD16+ and CD16− monocytes and the frequency of TNF+ cells among CD16+ and CD16− monocyte-derived macrophages from CD patients. Infliximab treatment resulted in elevated TNF and IL-10 macrophage response to bacteria. An infliximab-dependent increase in the frequency of circulating CD16+ monocytes (particularly the CD14++CD16+ subset) was also observed (before infliximab: 4·65 ± 0·58%; after three administrations: 10·68 ± 2·23%). In response to MAP infection, macrophages obtained from CD16+ monocytes were higher TNF producers and CD16+ macrophages from infliximab-treated CD patients showed increased frequency of TNF+ cells. In conclusion, infliximab treatment increased the TNF production of CD macrophages in response to bacteria, which seemed to depend upon enrichment of CD16+ circulating monocytes, particularly of the CD14++CD16+ subset. Infliximab treatment of CD patients also resulted in increased macrophage IL-10 production in response to bacteria, suggesting an infliximab-induced shift to M2 macrophages.