[Determination of specific IgM using column chromatography in immunologic diagnosis of toxoplasmosis]

The usefulness of detecting specific IgM antibodies in the immunodiagnosis of toxoplasmosis is fraught with false positive and false negative results. For instance false positivity can be obtained when rheumatoid factor is present in the serum while false negativity can occur because competing levels of IgG antibodies. We report the results obtained by the use of a simplified chromatographic method, commercially available in kits, for the separation of IgM from IgG in the immunodiagnosis of toxoplasmosis. The 1564 sera tested by indirect immunofluorescent technique (IFA) showed that 119 (7.6%) were positive if the whole serum was tested and only 7 (0.4%) after the chromatographic separation. This suggests that the use of this method can notably reduce the number of false results in sera with high IFA titer of IgM to toxoplasma.