What makes an IBD patient immunocompromised?From genome wide association studies there is increasing evidence of an aberrant immune response in IBD. 4 Susceptibility loci involve both the innate and adaptive immune response towards a diminished diversity of commensal microbiota. 5Description of the numerous mechanisms contributing to this dysimmunity is beyond the scope of this article.Despite evidence of defective mucosal immunity, there is no proof of a systemic immune defect in patients with IBD in the absence of concomitant immunomodulator therapy.Patients with IBD are therefore rendered immunocompromised through their treatment.Immunomodulators commonly used in inflammatory bowel disease are corticosteroids, thiopurines, methotrexate, calcineurin inhibitors, anti-tumor necrosis factor agents, or other biologics.Their modes of action differ, but they all compromise to some extent the patient's immune response.To date there is no accurate biological means to quantify immunosuppression in patients with IBD.

Second European evidence-based consensus on the prevention, diagnosis and management of opportunistic infections in inflammatory bowel disease