The use of high speed gel filtration for the detection of rubella-specific IgM.

Three new gels, Ultrogels AcA 22, AcA 34 and AcA 44 have been compared with Sephadex G-200 for the detection of rubella-specific IgM. Ultrogel AcA 44 did not achieve an adequate separation of IgM and IgG. Ultrogels AcA 22 and AcA 34 gave clear separation of IgM and IgG but only the latter could be operated at flow rates significantly higher than Sephadex G-200. With rubella convalescent sera fractionation with Ultrogel AcA 34 leads to a 2-4-fold loss of sensitivity for the detection of the first peak of rubella HI activity which is associated with recent infection. This is largely due to the occurrence of specific IgA antibody in the first peak of rubella HI activity after Sephadex G-200 fractionation but not after Ultrogel AcA 34 fractionation.