IgM-IFA, IgM-ELISA, DS-IgM-ELISA, IgM-ISAGA, performed on whole serum and IgM fractions, for detection of IgM anti-toxoplasma antibodies during pregnancy

The traditional IgM-ELISA has a better sensibility and specificity than IgM-IFA when these two tests are performed on whole sera, but in many cases (sera titer values of greated than 200 I.U./ml) the presence of IgM antitoxoplasma antibodies can be detected only after purification of IgM fractions. The separations of IgM fractions avoids either false positive results due to the rheumatoid factors or antinuclear antibodies, and false negative results due to the competition between IgG and IgM antibodies. The present investigation has shown that antibody titers obtained by IgM-IFA and traditional IgM-ELISA correlate well with DS-IgM-ELISA and IgM-ISAGA performed on whole serum. The false negative results that frequently occur with IgM-IFA and traditional IgM-ELISA performed on whole sera heving sera titer values of greater than 200 I.U./ml in IgG IFA are avoided when the same sera were tested by DS-IgM-ELISA and IgM-ISAGA. All the sera which gave positive results by DS-IgM-ELISA were also positive when tested with IgM-ISAGA. Our researches demonstrate the high specificity and sensitivity of IgM-ISAGA and DS-IgM-ELISA performed on whole serum.