[Chagas disease. Serologic response to crude and semipurified T. cruzi antigens in different clinical groups of patients].
The immune response of people infected by the protozoan parasite Trypanosoma cruzi varies in indeterminate or chronic periods of infection, according to the course of the disease. Apparently, the antibody pattern is different in asymptomatic patients than in patients with cardio-myopathy. The study of those differences for clinical purposes depends on the availability of adequate antigenic preparations. We studied the behavior of crude and partially purified antigens of T. cruzi in acute and chronically infected patients. The level of total antibodies was measured by conventional serology (indirect immunofluorescence, IF, and indirect hemagglutination, HA) and the level of antibodies against different fractions of antigens obtained by analytical chroma-tofocusing, by using enzymatic immunoassay (ELISA). Chronic patients were classified according to Kuschnir et al. in: Group 0 (G0) or Group 1 (G1) according to the absence or presence of electrocardiographic alterations. In acute patients, conventional serology was negative in most cases. However, the ELISA performed with the soluble fraction of the lysate of parasites, showed positive results in 60% of patients. By classical serology, the behavior of chronic patients sera was different in the two groups when assayed by IF; G1 showing more elevated titles than G0. On the other hand, by HA the results were similar in both groups. When the sera were studied by ELISA using the different fractions, the fraction collected at pH 4-4.5, named F IV, detected distinct reactivity in some of, but not in all, the patients of G1. In that subgroup, the highest ELISA indes (optical density of sera vs OD of negative controls) was observed. By associating IF plus FIV-ELISA the results became more apparent: 22% of sera showed titles by IF equal or more than 1:128 and ELISA index equal or more than 3.5, whereas only 2% of G0 showed this characteristic and all the sera with index equal or more than 4 belonged to G1. With lesser antibody titles it was not possible to differentiate between the two groups. It can be concluded that the study of the pattern of antibodies by using different antigens and serological methodologies can offer useful information in the different periods of Chagas disease, by adding the higher sensitivity of methods using crude antigens with the more specific and discriminative results obtained by the use of purified or synthetic antigens.
Cervetta
L
L
Servicio Nacional de Chagas, Córdoba.
Basso
B
B
Castro
I
I
Santamarina
N
N
Moretti
E
E
D000293:Adolescent; D000328:Adult; D000818:Animals; D000953:Antigens, Protozoan / Q000097:blood*; D014355:Chagas Disease / Q000097:blood / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D008875:Middle Aged; D014349:Trypanosoma cruzi / Q000276:immunology*
D000953:Antigens, Protozoan
Enfermedad de Chagas. Reactividad serológica hacia antígenos crudos y semipurificados del T. cruzi en distintos grupos clínicos de pacientes.