Comparación de la utilidad diagnóstica de las immunoglobulinas A y M en la toxoplasmosis aguda

Abstract

We compared the levels of IgA and IgM antibodies in nonimmunosuppressed patients with active toxoplasmosis to evaluate their diagnostic value. In group I (nine patients with toxoplasmosis) we determined the presence of anti-toxoplasma antibodies at the onset of the disease; in four of them we also studied the levels three months later. In group II (control) we tested 50 serum samples from healthy subjects. In both groups we investigated the presence of IgG with indirect enzyme immunoassay (EIA) (Eti-Toxok G, Sorin Biomedica); capture EIA was used to study IgA (Platelia Toxo IgA, Pasteur), and this method (Eti-toxok M, Sorin Biomédica) and the capture agglutination technique were used to study IgM (Toxo-ISAGA, Biomerieux). The nine patients in group I were positive for IgM (Sorin test) but one was negative with the capture agglutination technique and for IGA. All nine were positive for IgG, and IgG titers were increased in the patients studied a second time. In group II, none of the subjects had IgM; the levels of IgG were > 15 IU/mL in 18 subjects, and < or = 15 IU/mL but not absent, in the 32 remaining subjects. IgA was detected in eight of the 18 individuals with IgG levels > 15 IU/mL and in 11 of the 32 with levels < or = 15 IU/mL. The sensitivity of IgA was 88.8% and its specificity 62%; positive and negative predictive values were 29.6% and 96.8%, respectively. The assay of IgA in the course of active toxoplasmosis does not appear to be a more useful marker than IgM detection; however, the study population should be enlarged to include patients with reactivations of toxoplasmosis, before we can be more conclusive.