CD40LG and toxoplasmosis: Several investigators have already shown that the accuracy of the tests differ markedly, depending on the use of selected or routine sera.14Therefore, positive IgM test results should be confirmed by additional tests (such as the IgM immunosorbent agglutination assay [ISAGA] and differential agglutination, for example) in laboratories experienced in the diagnosis of toxoplasmosis, or by demonstration of a significant increase in antibody titers in serial serum samples with intervals of at least 3 weeks that run parallel to prevent misinterpretation.6, 15