Equivalent Cell Mediated Immunity to Varicella Zoster Virus in Young Patients With Inflammatory Bowel Disease Compared to Healthy Controls for Whom the Herpes Zoster Vaccine Is Recommended

Abstract

Introduction: Patients with inflammatory bowel disease (IBD) are treated with immunosuppressants that increase their risk of herpes zoster (HZ). In fact, forty-year-old IBD patients have a greater risk of HZ than healthy fifty-year-olds, an age when HZ immunization is currently recommended. A HZ subunit vaccine was recently approved and can be safely administered to immunosuppressed patients with IBD. Reactivation of varicella zoster virus (VZV) results in HZ, and strong cell-mediated immunity prevents reactivation of HZ. The aim of this study was to evaluate the cell-mediated immunity to varicella zoster virus in immunosuppressed patients with IBD compared to healthy controls. Methods: We performed a cross sectional study evaluating the cell mediated immunity to varicella zoster virus using the gold standard assay, interferon-g ELISPOT. Our study consisted of thirty-two patients divided into three groups: Patients with IBD age 35-49 years with prior history of chicken pox on: 1) thiopurine monotherapy or 2) combination therapy (anti-TNF and immunomodulator (thiopurine or methotrexate) and 3) healthy controls age 50-59 years. All patients with IBD were on stable doses of their immunosuppressive regimen for at least 3 months. The primary outcome of the study was to evaluated cell mediated immunity to varicella zoster virus between healthy controls and each group of patients with IBD based on their immunosuppressive regimen. Results: By design, the healthy individuals are older than the patients with IBD, but the groups are comparable with respect to other characteristics (Table 1). Healthy individuals (median 42.5 (IQR 28.4-99.3)) had similar interferon-g VZV ELISPOT results compared to the patients with IBD treated with thiopurines (median 41.5 (IQR 9.8-71.3)) or combination therapy (median 72.0 (IQR 18.0-92.0)); Kruskall-Wallis p=0.72) which is indicative of the vigor of the cell-mediated immune response to VZV. Conclusion: This is the first study to evaluate cell-mediated immunity to VZV in patients with IBD. Young immunosuppressed patients with IBD have similar cell mediated immunity to VZV as healthy fifty year olds, an age when HZ immunization is recommended. Our study suggest young immunosuppressed patients with IBD may benefit from early HZ immunization since they might be at increased risk of HZ due to low cell mediated immunity to VZV.594 Figure 1. IBD Patient Demographic