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P161. Immune response to influenza A/H1N1 2009 vaccine in patients with inflammatory bowel disease on anti TNF-α therapy in vivo and in vitro

P161. Immune response to influenza A/H1N1 2009 vaccine in patients with inflammatory bowel disease on anti TNF-α therapy in vivo and in vitro

G. Andrisani1, D. Frasca2, A. Armuzzi1, A. Papa1, M. Marzo1, C. Felice1, G. Mocci1, D. Pugliese1, I. De Vitis1, G. Rapaccini1, B. Blomberg2, L. Guidi1

1OU of Internal Medicine and Gastroenterology, Complesso integrato Columbus, Università Cattolica del Sacro Cuore, Roma, Italy; 2Department of Microbiology and Immunology, Miller School of Medicine, University of Miami, Miami, FL, United States

Aim: Patients with inflammatory bowel disease (IBD) may be immunocompromised because of their treatment and for this reason, they might be considered as susceptible to and at high-risk from complications of H1N1 virus infection. The immune response in these patients to vaccine is still unclear. Aim of this study was to assess the in vivo and in vitro response to the vaccine.

Material and Methods: We enrolled 20 healthy controls and 16 patients, 8 affected by Ulcerative Colitis (UC) and 8 by Crohn's disease (CD), all undergoing maintenance treatment with anti TNF-α. Patients were on anti TNFα monotherapy (n = 10) or anti TNFα associated with immunosuppressor or corticosteroids (combined therapy) (n = 6). Mean age of patients was 46±15, of normal controls 40±4. All individuals were vaccinated with the monovalent vaccine A/California/7/2009 (H1N1), Novartis. Blood samples were obtained during the 2009/10 vaccination campaign before (T0) and 4–6 weeks (T1) after vaccination. Immune response to vaccination was measured in vivo by hemoagglutination inhibition assay (HI) and ELISA. The results are expressed as fold-increase after vaccination (titer at T1/titer at T0). In vitro, we evaluated the specific response of B cells to the vaccine, as measured by AID (activation-induced cytidine deaminase) determination by qPCR. The results are expressed as fold-increase after vaccination.

Results: Nine/10 (90%) of patients in monotherapy and 3/6 (50%) in combined therapy responded to vaccination by HI, whereas all healthy controls responded. Six/10 (60%) patients in monotherapy also responded in H1N1-specific ELISA for IgA and IgG, whereas 4/10 (40%) or 3/6 (50%) patients in combined therapy responded in H1N1-specific ELISA for IgA or IgG, respectively. Six/10 (60%) patients in monotherapy and 1/6 patients (17%) in combined therapy showed an in vitro response as evaluated by AID by qPCR, as compared to 17/20 (85%) healthy controls. The HI and in vitro response were correlated in 72% of IBD patients and in 85% of the healthy controls.

Conclusion: All IBD patients showed reduced responses to the vaccine as compared to healthy controls. Among IBD patients, those in combined therapy showed the most significant reduction in the response as compared to those undergoing monotherapy. We can propose the vaccination to protect these immunocompromised patients.