RESUMO
The persistence, in some subjects, of specific IgM antibodies to Toxoplasma gondii for several months after the acute phase of infection has complicated the interpretation of serological test results for toxoplasmosis. Several reports have emphasized the value of the detection of Toxoplasma-specific IgA antibodies for the diagnosis of acute toxoplasmosis. In this article, we report the follow-up profiles of Toxoplasma-specific IgM and IgA antibodies in serum samples obtained from 12 patients at various intervals after the onset of the clinical manifestations of infection. IgM antibodies were detected by the indirect immunofluorescence (IIF) test, antibody capture enzyme-linked immunosorbent assay (cELISA) and enzyme-mediated chemilluminescent technique (CmL). IgA antibodies were quantified by the direct ELISA (dELISA) and cELISA procedures. As defined by the manufacturer of the cELISA test for IgA used, most patients with acute toxoplasmosis have antibody levels > 40 arbritary units per ml (AU/ml). At values > 40 AU/ml, the cELISA for IgA detected significant antibody levels for a shorter time than the other techniques used for IgM and IgA detection. However, IgA levels < or = 40 AU/ml do not exclude the possibility of acute toxoplasmosis since such levels can be reached very soon after infection with T. gondii. The results obtained in the present study show that the serological diagnosis of acute toxoplasmosis may not be such an easy task. Our data suggest that use of the IgA-cELISA concomitantly with IgM antibody screening could permit, in some circumstances, a more efficient diagnosis of acute acquired toxoplasmosis.
Assuntos
Anticorpos Antiprotozoários , Imunoglobulina A/sangue , Imunoglobulina M/sangue , Toxoplasma/imunologia , Toxoplasmose/diagnóstico , Doença Aguda , Animais , Anticorpos Antiprotozoários/imunologia , Seguimentos , Humanos , Fatores de Tempo , Toxoplasmose/imunologiaRESUMO
AIMS: To assess the performance and efficacy of three immunological techniques for the detection of Toxoplasma specific IgA antibodies in acute toxoplasmosis. METHODS: The following techniques were used to examine 128 serum samples (51 cases of acute toxoplasmosis, 50 cases of heterologous infections, and 27 healthy controls): direct enzyme linked immunosorbent assay (ELISA), antibody capture ELISA, and antibody capture agglutination. RESULTS: Direct ELISA had a sensitivity of 98% and a specificity of 97%, antibody capture ELISA of 100% and 99%, respectively, and antibody capture agglutination had sensitivity and specificity of 100%. CONCLUSIONS: All three immunological techniques performed well with similar efficacy. Detection of Toxoplasma specific IgA antibodies is a useful diagnostic marker for acute toxoplasmosis.
Assuntos
Testes de Aglutinação , Anticorpos Antiprotozoários/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Imunoglobulina A/sangue , Toxoplasma/imunologia , Toxoplasmose/sangue , Doença Aguda , Animais , Biomarcadores/sangue , Humanos , Sensibilidade e EspecificidadeRESUMO
Total serum IgE, and Strongyloides-specific IgG and IgA antibodies were studied in 27 patients with parasitologically proven strongyloidiasis. Clinical manifestations in this case series were investigated by a retrospective study of the patient's records. Total serum IgE levels were elevated (greater than 250 IU/ml) in 59% of the patients (mean concentration = 1364 IU/ml). Parasite-specific IgG and IgA antibodies were detected by ELISA in the serum of 23 (85.2%) and 21 (77.8%) patients, respectively. Elevated serum IgE and clinical manifestations were not useful indexes of the presence of strongyloidiasis. On the other hand, our results support the view that serologic tests, particularly ELISA for detecting Strongyloides-specific IgG antibodies, can be usefully exploited for diagnostic purposes in strongyloidiasis.
Assuntos
Anticorpos Anti-Helmínticos/análise , Strongyloides stercoralis/imunologia , Estrongiloidíase/diagnóstico , Animais , Ensaio de Imunoadsorção Enzimática , Humanos , Técnicas Imunoenzimáticas , Imunoglobulina A/análise , Imunoglobulina E/análise , Imunoglobulina G/análise , Estudos Retrospectivos , Testes SorológicosRESUMO
Aqueous-soluble (AS) antigens from larvae of Strongyloides stercoralis, extracted with phosphate-buffered saline, are traditionally used for serodiagnosis of strongyloidiasis. To identify sources of antigens for use in serodiagnosis, residual particulates from parasite larvae after aqueous extraction were solubilized with Tris-buffered 8M urea, yielding a urea-soluble (US) antigen fraction. Both AS and US antigens from S. stercoralis were evaluated by an enzyme-linked immunosorbent assay. No significative differences were observed between AS and US antigens from the parasite regarding specific antigenic activity and cross-reactivity. Immunoassays are highly dependent on the antigen for sensitivity and specificity. Crude extracts from S. stercoralis should be further studied, mainly in relation to antigenic fractions which could provide even more sensitive and specific results. Studies of fractionation of S. stercoralis must take into account the antigen yield of both the crude extract and fractions, since larvae of parasite are normally difficult to obtain. Considering this aspect, the results from this study are very useful, since the extraction with urea substantially increased the amounts of antigenic materials normally obtained with the classical aqueous extraction.
Assuntos
Antígenos de Helmintos , Strongyloides stercoralis/imunologia , Estrongiloidíase/diagnóstico , Animais , Antígenos de Helmintos/isolamento & purificação , Diagnóstico Diferencial , Ensaio de Imunoadsorção Enzimática/métodos , Estudos de Avaliação como Assunto , Humanos , Larva/imunologia , SolubilidadeRESUMO
A retrospective study of laboratory records in a 400-bed university hospital in Campinas city, SP (Southeastern Brazil) suggests that infection by Strongyloides stercoralis is widespread in the region. A prevalence of 10.81% was found in 37,621 stool specimens examined in a two-year period. Parasite-specific IgG antibodies were measured by ELISA in sera from 90 patients with strongyloidiasis. The ELISA detected antibody in 76 (84.44%) patients, indicating that serodiagnostic tests may be helpful in screening patients for strongyloidiasis.