Impaired Antibody Responses to Pneumococcal Polysaccharide in Elderly Patients with Low Serum Vitamin B₁₂ Levels

Abstract

Objective: To determine whether immunocompetent elderly patients with low serum vitamin B₁₂ levels have impaired serum antibody responses to the 23-polyvalent pneumococcal polysaccharide vaccine.

Design: Controlled, prospective cohort study.

Measurements: 15 patients with low serum vitamin B₁₂ levels and 15 age- and diagnosis-matched patients with normal levels were vaccinated. Serum antibody titers to 12 pneumococcal serotypes were measured by radioimmunoassay before and 4 weeks after vaccination.

Results: The difference between the geometric mean of the vaccine antibody titers before and after vaccination for all 12 serotypes was lower (P = 0.005) in the patients with low vitamin B₁₂ levels than in the patients with normal levels. When mean corpuscular volume and age were controlled for, vitamin B₁₂ remained an independent predictor of antibody response (P = 0.005). Erythrocyte mean corpuscular volume was also an independent predictor of the increase in titer (P = 0.03).

Conclusions: Patients with low vitamin B₁₂ levels had impaired antibody responses to pneumococcal vaccine. Further study is necessary to determine whether treatment with vitamin B₁₂ can enhance specific immunoglobulin synthesis and improve the clinical efficacy of the pneumococcal vaccine in patients with low vitamin B₁₂ levels.