Opsonic activity of immunoglobulin prepared for intravenous use

The opsonic activity of two immunoglobulin preparations modified for intravenous infusion was tested against Streptococcus pneumoniae types 3, 7F, and 14 and two strains of Staphylococcus aureus by polymorphonuclear leukocyte uptake of 3H-thymidine-labeled bacteria. Reduced and alkylated immunoglobulin (Chem-IgG) and immunoglobulin prepared by chromatography with diethylaminoethyl-Sephadex (DEAE-IgG) were evaluated with and without complement and compared with the opsonic activity of immune serum globulin and heated pooled human serum. Opsonic activity of DEAE-IgG was greater than that of Chem-IgG and equivalent to the activity of immune serum globulin and pooled human serum against S. aureus 502A and type 3 pneumococcus. Both intravenous immunoglobulins had lower opsonic activity than either pooled human serum or immune serum globulin against type 14 pneumococcus. There were no differences in antibody avidity for pneumococcal antigen among the immunoglobulins tested. All four opsonins had similar opsonic activity against the protein A-deficient S. aureus Wood 46. Modification of immunoglobulin for intravenous infusion by chemical alteration may adversely affect opsonic activity by changing the Fc portion of the antibody molecule.