Evaluation of immunoblotting for the detection ofToxoplasma gondii immunoglobulin M antibodies

Immunoblot analysis was used to detect human IgM antibodies toToxoplasma gondii in 20 patients with recent toxoplasmosis, 30 immune individuals, 30 non-immune individuals, and 24 children less then two years old. Analysis of the IgM strips revealed that specific IgM antibodies detectable after a recentToxoplasma gondii infection react with the same antigens as the natural antibodies present in the sera of immune and non-immune individuals and in the sera of young children. These data indicate that immunoblotting is not useful as a reference method forToxoplasma gondii IgM detection, and suggest that improvement of the specificity of IgM detection will remain difficult.