Distribution of IgG subclasses in commercial and some experimental gamma-globulin preparations

The IgG subclass distribution was determined in six commercial and in four experimental human gamma-globulin preparations. The concentrations of IgG subclasses were measured in a modified radiommunoassay using subclass-specific antisera. In commercial gamma-globulins, the distribution of the subclasses corresponded roughly to the distribution in normal human serum. A considerable enrichment of the IgG 4 was found in experimental lots prepared either from the ethanol fraction III or from the rivanol-precipitable IgG.