[Use of the ISAGA method in detection of specific IgM, IgA, IgE antibodies in acquired and congenital toxoplasmosis].

Immunocapture assays ISAGA PLUS IgA/IgM (bioMérieux) and IgE ISAGA were used to determine their usefulness in the diagnosis of acquired and congenital toxoplasmosis. Specific IgM, IgA and IgE antibodies were tested in 134 patients, namely pregnant women who seroconverted during gestation (n = 20), children with congenital toxoplasmosis (n = 5), patients with toxoplasmic lymphadenitis (n = 56) and immunocompetent individuals with chronic Toxoplasma gondii infection (n = 53). Altogether 172 sera were examined. Specific IgM antibodies were detected in all sera from pregnant women (100%) with recent T. gondii infection (1-8 weeks after seroconversion), in all patients with toxoplasmic lymphadenopathy (1-3 months after onset of symptoms) and in their control examinations after 2 and 5 months (100%) and also in 35 (66%) out of 53 patients with chronic infection. In infants with congenital toxoplasmosis IgM were found only in one new-born; equivocal results were obtained in 3 children during the asymptomatic serological reactivation in the second year of life. Specific IgA antibodies were present in sera from 15 (75%) out of 20 women seroconverted during pregnancy; in 3 cases the results were equivocal. IgA antibodies were detected in sera from 30 (81.1%) out of 37 patients with toxoplasmic lymphadenitis examined once; in 19 patients examined 3 times IgA antibodies were present in all the cases in the first serological examination performed when clinical symptoms were first observed (100%), in 17 patients after 2 months (89.5%) and in 11 patients after 5 months (57.9%). IgA antibodies were also detected in 21 sera (39.6%) from patients with chronic T. gondii infection. In children with congenital toxoplasmosis IgA antibodies were found in 3 cases during serological reactivation after discontinuation of pyrimethamine-sulfadiazine therapy; in these cases equivocal results of IgM antibodies were present, and positive result of IgE antibodies in one case. Specific IgE antibodies were detected in sera from 17 (85%) out of 20 women with seroconversion and in 18 patients with lymphadenopathy (32.1%); in the last group IgE antibodies were not present in the follow-up examination after 5 months. IgE antibodies were detected only in 5 cases (9.4%) with chronic infection. IgA and IgE antibodies in ISAGA begin to appear about a week later than IgM antibodies: in sera collected between the 2nd and 3rd week after invasion the positive results were obtained in all cases (100%). Therefore, ISAGA PLUS IgA/IgM (bioMérieux) is useful for the diagnosis of recent T. gondii infection especially in women with suspected seroconversion during pregnancy. ISAGA PLUS IgA/IgM is more sensitive than any conventional method routinely used and so far is a specially efficient technique for newborns and infants suspected for congenital infection and/OR IN DIAGNOSING CONGENITAL TOXOPLASMOSIS DURING IMMUNOLOGICAL RECRUDESCENCE. tHIS TEST HAS A LIMITED VALUE IN TOXOPLASMOSIS WITH LYMPHADENOPATHY BY REASON OF POSSIBILITY OF A LONG PERSISTENCE OF iGm and IgA antibodies detected by ISAGA. Detection of specific IgE antibodies using ISAGA technique may be useful for differential diagnosis of acute and chronic phase of T. gondii infection and also in some cases of serological reactivation of congenital toxoplasmosis.