Immune response to influenza vaccine and pneumococcal polysaccharide vaccine under IL-6 signal inhibition therapy with tocilizumab

Objectives. To evaluate humoral immune response to influenza vaccine and polysaccharide pneumococcal vaccine in patients with rheumatoid arthritis (RA) or Castleman's disease (CD) during tocilizumab therapy. Methods. Thirty-eight patients (28 RA and 10 CD) receiving tocilizumab and 39 RA patients receiving TNF inhibitors and/or synthetic DMARDs subcutaneously received a single dose of a split-virion inactivated influenza vaccine containing A(New Caledonia (NC):H1N1), A(Hiroshima (HIR):H3N2) and B(Malaysia (MAL)) strains. Twenty-one RA patients using tocilizumab also received 23-valent polysaccharide pneumococcal vaccine. Antibody titers were measured every 4 weeks for a total of 12 weeks after vaccination. Results. In the tocilizumab group, seroprotective titers (40-fold or more) were obtained in 36/38(95%) for A(NC), 35/38(92%) for A(HIR) and 32/38(84%) for B(MAL). In the patients with baseline antibody titer < 40-fold, 11/11(100%), 7/8(88%) and 18/20(90%) patients showed fourfold or more increase in the titer from baseline to A(NC), A(HIR) and B(MAL), respectively. Patients using TNF inhibitors and/or DMARDs showed similar responses. Pneumococcal antibody titers increased at least two-fold in more than 9 of 12 serotypes, which continued for longer than 12 weeks in all the patients. Conclusion. Interleukin-6 (IL-6) blocking therapy with tocilizumab did not affect the humoral immune response to both influenza and pneumococcal vaccines.