Functional antibodies to Haemophilus influenzae type B, Neisseria meningitidis, and Streptococcus pneumoniae contained in intravenous immunoglobulin products

Abstract

Intravenous immunoglobulin G (IVIG) replacement therapy is used to prevent invasive infections in patients with primary antibody deficiency (PAD). However, few studies have functionally evaluated specific antibodies against encapsulated bacteria that cause invasive infection in patients with PAD. In this study, functional antibodies against Haemophilus influenzae type b (Hib), Streptococcus pneumoniae (pneumococci), and Neisseria meningitidis (meningococci) in IVIG therapy were evaluated. Sixteen lots of IVIG products prepared by two Korean manufacturers (Products A and B) were evaluated. The functional antibodies were measured by serum bactericidal assay for Hib and four meningococcal serogroups and by multiplexed opsonophagocytic assay for 26 pneumococcal serotypes. The estimated trough levels of antibodies against Hib, pneumococcus, and meningococcus were calculated to determine whether the usual IVIG dose is appropriate for protecting patients with PAD. The functional antibody levels for Hib were similar in all of the IVIG products. In contrast, serum bacterial indices of meningococcal serogroups A and Y showed significant differences between products A and B. Opsonic indices to pneumococci varied depending on the serotype in each IVIG product. The estimated trough levels of antibodies against Hib, pneumococcus, and meningococcus exceeded the protective levels in most of the IVIG products except for the antibodies against two pneumococcal serotypes. Most of the tested commercial IVIG products had sufficient functional antibodies against Hib, pneumococcus, and meningococcus to protect patients with PAD receiving IVIG treatment. Regular and continuous evaluation of IVIG products is necessary to maintain an optimal therapeutic effect.