The detection of rubella-specific IgM by an immunosorbent assay with solid-phase attachment of red cells (SPARC).

An immunosorbent assay using solid-phase attachment of red cells (SPARC) was used for the detection of rubella-specific IgM. The method is described and the results compared with those obtained by the IgM antibody capture radioimmunoassay (MACRIA). One hundred and ninety-nine sera were investigated for the presence of rubella-specific IgM and only one discrepant result occurred, namely a false positive obtained by MACRIA in a patient with infectious mononucleosis. Rheumatoid factor, heterophile antibody, and rubella-specific IgG did not interfere with the results obtained by the SPARC technique. Advantages of the SPARC technique include the case and lack of expense of testing large numbers of sera, the small volume of sample required and the fact that pretreatment of serum is not necessary.