Objective: To evaluate the influence of abatacept (ABA) and associated contributing factors on pandemic 2009 influenza A/H1N1 vaccine immunogenicity in rheumatoid arthritis (RA) patients.
Methods: The response to a nonadjuvanted monovalent pandemic 2009 influenza A/H1N1 killed virus vaccine was analyzed in 11 RA patients using ABA (RA-ABA), most with concomitant nonbiologic disease-modifying antirheumatic drugs (DMARDS), and compared to 33 age-matched RA patients on methotrexate (MTX) and 55 healthy controls, all without previous seroprotection. Clinical and laboratory evaluations were performed before and 21 days after vaccination. Anti-influenza antibody titers were measured by hemagglutination inhibition assay. Seroprotection (antibody titers ≥1:40) and the factor increase (FI) in the geometric mean titers (GMTs) were calculated. Prevaccination lymphocyte counts and gammaglobulin levels were determined.
Results: Sex distribution, disease duration, and the Disease Activity Score in 28 joints were similar in the RA groups (P > 0.05). After vaccination, seroprotection was significantly reduced in RA-ABA patients compared to RA-MTX patients (9% versus 58%; P = 0.006) and controls (69%; P ≤ 0.001). FI-GMT was severely reduced in RA-ABA patients compared to RA-MTX patients (1.8 [1.4-2.3] versus 8.7 [5.2-17.4]; P < 0.001) and controls (11.5 [8.0-16.7]; P ≤ 0.001). Lymphocyte counts were comparable in RA groups (P > 0.05), but RA-ABA patients had slightly lower gammaglobulin levels than RA-MTX patients (0.9 gm/dl [0.6-1.8] versus 1.2 gm/dl [0.8-1.7]; P = 0.03), although almost all were within the normal range values.
Conclusion: The current study established that ABA, in association with traditional DMARDs, significantly reduces the humoral response to pandemic 2009 influenza A/H1N1 vaccine in RA patients. The results suggest an influence of costimulatory modulation in humoral response to this vaccine.
Trial registration: ClinicalTrials.gov NCT01151644.
Copyright © 2013 by the American College of Rheumatology.