Evaluation of Quaternary Aminoethyl-Sephadex A50 Column Chromatography for Detection of Anti-Cytomegalovirus Immunoglobulin M

The sensitivity of an indirect fluorescent antibody (IFA) test (screening test) for the detection of antibodies to cytomegalovirus (CMV) was examined by using 128 serum specimens and quaternary aminoethyl (QAE)-Sephadex A50 column chromatography to separate IgM from IgG class antibodies. Of these 128 rheumatoid factor-negative serum samples, only 54 (42%) continued to produce fluorescence after the IgG was removed by the Sephadex column (yielding a theoretical 1:10 dilution) and the samples were retested for IgM (confirming test). Of the 54 specimens that were positive on both the screening and confirming IgM IFA assays, 53 (98%) had titers of 1:80 or more. Of the 74 sera that were negative on the confirming test, only 10 (14%) had titers of 1:80 on the initial screening test, and none was greater than 1:80. Immunoglobulin measurements of eight serum samples before and after column treatment indicated excellent IgG removal but poor IgM recovery (a mean loss of 85% of the total IgM). Comparison of the time needed to detect IgM in CMV culture-positive patients demonstrated an increase from 17.1 to 28.3 days (serum tested by IFA before and after column separation, respectively). Therefore, confirmation of anti-CMV IgM in serum specimens by QAE-Sephadex A50 column chromatography seems to be of low sensitivity.