Opsonic activity of commercially available standard intravenous immunoglobulin preparations

Several standard intravenous immunoglobulin G (IVIG) products are available in the United States and have been used with the intent to treat or prevent infections in neonates. We evaluated more than 100 lots of IVIG, from 6 products, to determine the amount of opsonic antibody against neonatal pathogens. Neutrophilmediated opsonophagocytosis was used to determine opsonic activity in these preparations forStaphylococcus epidermidis; Haemophilus influenzae type b; Streptococcus pneumoniae serotypes 3, 14 and 19; Group B Streptococcus sero-types Ia, Ib, Ia/c, II and III; and Escherichia coli (K1). Pathogen-specific osponic activity of the lots tested ranged from undetectable to 1:80 and was detectable in < 10% to >90% of lots tested depending on the organism and manufacturer. Within an IVIG lot there was variable opsonic activity against different strains or serotypes of the same organisms. Opsonic activity was significanlty (≤ 0.05) affected by the manufacture's donor pool and less so by the manufacturing method. We conclude that the pathogen-specific opsonic antibody activity of an IVIG lot is: (1) highly variable for several common neonatal pathogens; (2) predominantly dependent on the donor pool and not the manufacturing method. Clinicians may more appropriately select therapy if the pathogen-specific antibody content of IVIG products by lot are known. In the future neonatal IVIG research should focus on using preparations with known pathogen-specific anti-body activity.