Rapid detection of rubella-specific IgM antibodies by the use of microimmunobeads (MIB-IgM)

A simple haemagglutination (HA) titre reduction assay for the detection of rubella-specific IgM antibodies has been developed. Serum IgM is rapidly isolated by immune adsorption to heavy chain-specific anti-human IgM antibodies covalently coupled to polyacrylamide microimmunobeads. The immobilized immunocomplexes are incubated with rubella virus HA antigen. Subsequently, the particles are centrifuged from the solution, and the reduction of the HA titre is determined. This procedure has proven to be as reliable as haemagglutination inhibition (HAI) tests carried out with IgM fractions separated on a sucrose density gradient.