The interference of IgM rheumatoid factor in enzyme-linked immunosorbent assays of rubella IgM and IgG antibodies
- M. Vejtorp
- J Virol Meth
Detection of rubella virus-specific IgM employing trypsin-treated human group 0 erythrocytes was evaluated using the method of sera fractionation on sucrose density gradients (SDG) and that of sera absorption with staphylococcal protein A. The former method proved to be highly specific and sensitive in confirming or excluding rubella by demonstration of specific IgM. In contrast, the latter method provided comparable results in only 71a43% of specimens tested by both methods while false-positive or -negative IgM results were obtained in the remaining 28 57% of specimens. In view of these results, therefore, it is recommended that all those specimens found positive for specific IgM by the protein A method must be confirmed by another procedure, possibly that of specific IgM reduction with 2-mercaptoethanol.