Elution patterns of rubella IgM, IgA, and IgG antibodies from a dextran and an agarose gel

The elution pattern of serum proteins and the distribution of rubella HAI activity in 95 sera from 65 cases were determined after gel filtration with (a) Sephadex G-200 and (b) Bio-Gel A-5M. Rubella HAI antibody in peak 1 after Sephadex G-200 fractionation of early convalescent sera consists of both IgM and high molecular weight IgA. However, these two classes of antibody can be distinguished by gel filtration with Bio-Gel A-5M. Bearing these differences in mind, the results of fractionation with the two gels correlate very well although the use of Bio-Gel A-5M gives a slightly less sensitive technique for the diagnosis of recent infection.