Rubella-specific IgG subclass concentrations in sera using an enzyme-linked immunosorbent assay (ELISA): the effect of different sources of rubella antigen.

Five rubella antigens were evaluated in an antiglobulin enzyme-linked immunosorbent assay for rubella-specific IgG subclass antibody. One monoclonal anti-human IgG subclass antibody was used for each of IgG1, IgG2 and IgG4, but two were compared for IgG3. A total of 101 sera were tested from cases of rubella in the distant past and from cases of primary rubella, reinfection and following immunization. Only one serum gave a discrepant result for specific IgG1, being positive with only one rubella antigen, a commercially prepared antigen coated on to microtitre wells (Enzygnost; Behringwerke). No sera contained detectable specific IgG2. Only four sera contained specific IgG4, and this was detectable only with Enzygnost antigen. For specific IgG3 little difference was observed between the two monoclonal anti-human IgG3 subclass antibodies; only two very weakly positive sera gave discrepant results. However, varying results were obtained for specific IgG3 with the different antigens. Enzygnost gave more positive results for specific IgG3 with most categories of sera. It is concluded that the differences between various reports of the rubella-specific IgG subclass profile cannot be explained entirely by the use of different rubella antigens.