Detection of IgM antibodies against cytomegalovirus: comparison of two radioimmunoassays, enzyme-linked immunosorbent assay and immunofluorescent antibody test.

The sensitivity and specificity of direct antibody radioimmunoassay (RIA), M-antibody capture RIA (MACRIA), enzyme-linked immunosorbent assay (ELISA), and the immunofluorescent antibody (IFA) test for the detection of CMV-specific IgM was compared using 40 sera selected from different groups of patients. RIA, MACRIA, and ELISA gave concordant results with thirty-two sera but discordant results with eight sera, of which three were cord sera from congenitally infected babies, three were from immunocompromised patients with recurrent CMV infections, and two were from patients with lymphadenopathy and Paul-Bunnell-positive mononucleosis, respectively. RIA, MACRIA, and ELISA were of similar sensitivity with sera from adult patients, but ELISA was apparently less sensitive than RIA and MACRIA for the detection of CMV IgM in cord serum. By comparison IFA was significantly less sensitive than the other three tests. Rheumatoid factor is reactive in RIA, ELISA, and IFA but can efficiently be removed by absorption with latex-IgG beads or cross-linked human IgG.