IgG subclasses in human gamma-globulin preparations for intravenous use and their reactivity with staphylococcus protein A.

In two of four non-enzymatically treated gamma-globulin preparations C Immunoglobulin Schura, Immunoglobulin SRK), the distribution of IgG subclasses was found to be close to that of normal human serum. In two other preparations (sulphonated and beta-propiolactone-treated) IgG3 was not detectable by means of appropriate antiserum. The IgG residual portion of plasmin-treated gamma-globulin was enriched in IgG2, while IgG3 was absent. In affinity chromatography on protein A Sepharose, IgG3 in the unbound and IgG1, IgG2 and IgG4 in the bound fractions were found in Immunoglobulins Schura and SRK. In the sulphonated preparation no IgG was found in the unbound fraction, while IgG1, IgG2 and IgG4 were eluted from the bound fraction. In beta-propiolactone-treated gamma-globulin IgG1, IgG2 and IgG4 were present in both fractions. The testing of reactivity of IgG subclasses with Staphylococcus protein A can supply important information about the state of the Fc part in immunoglobulin preparations.