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

Abstract

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.