Correlation between opsonic activity for various microorganisms and composition of gammaglobulin preparations for intravenous use.

In this study 12 commercial immunoglobulin preparations for intravenous administration were investigated with respect to their opsonic activity for various strains of Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, and group B streptococci, and in addition, the concentration of unsplit IgG molecules, IgG fragments, and IgG aggregates (dimers) was determined. The results show that four preparations that had been treated with enzyme or by reduction and alkylation had hardly any opsonic activity; the other preparations were as effective as inactivated serum. A statistical analysis showed an excellent correlation between the concentration of intact IgG molecules in a preparation and the opsonic activity for the various bacteria; a negative correlation between the concentration of IgG fragments and the opsonic activity was found. The combination of the two techniques used in this study provides a basis for recommendations on the choice of gammaglobulin preparations for clinical use.