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Longitudinal study of immune response in human Chagas' disease
Insights
Chagas
Area of Science:
- Immunology
- Infectious Diseases
- Cardiology
Background:
- Chagas' disease, caused by Trypanosoma cruzi, affects millions globally.
- Cardiac involvement is a major complication, but immune responses remain incompletely understood.
Purpose of the Study:
- To longitudinally assess immune responses, clinical status, and heart tissue reactivity in Chagas' disease patients.
- To compare immune profiles between patients with and without cardiomyopathy.
Main Methods:
- Longitudinal study of 42 Chagas' disease patients over 1 year.
- Assessed humoral immunity (serology), cell-mediated immunity (lymphoblastogenesis to T. cruzi and heart antigens), and parasitemia (xenodiagnosis).
- Patients categorized into Group 1 (no heart disease) and Group 2 (cardiomyopathy).
Main Results:
- Higher anti-T. cruzi antibody titers in Group 2 patients.
- Parasitemia detected more frequently in Group 2 (50%) vs. Group 1 (20%).
- Positive xenodiagnosis associated with lower T. cruzi lymphoblastogenesis in Group 1, suggesting lost immune regulation in cardiomyopathy.
Conclusions:
- Immune responses to T. cruzi differ between Chagas' disease patients with and without cardiomyopathy.
- Parasitemia and altered immune regulation may contribute to cardiac disease progression.
- No direct correlation found between heart reactivity and clinical cardiac status.
Abstract:
Immune response, clinical status, and reactivity to heart tissue were studied longitudinally for 1 year in 42 patients with Chagas' disease (South American trypanosomiasis). The patients were divided into two groups. Group 1 was composed of patients with chagasic infection with no evidence of heart disease. Group 2 patients had chagasic infection and cardiomyopathy. Humoral immune response to Trypanosoma cruzi was measured serologically, and cell-mediated immune responses to T. cruzi and rat heart antigens were evaluated by lymphoblastogenesis. Parasitemia was detected by xenodiagnosis. Serological tests for anti-T. cruzi antibodies were positive in all patients of both groups, and the titers were significantly higher in group 2. A change of titer during the study period was more frequently associated with a positive xenodiagnosis in both groups. Lymphoblastogenesis in response to T. cruzi antigen was positive at least once in all patients of both groups. When rat heart antigen was used, 44.4% of the patients in group 1 and 40.0% of those in group 2 were positive on at least one occasion. Xenodiagnosis revealed that 20% of the patients in group 1 and 50% of those in group 2 (P = 0.01) had detectable circulating parasites during the course of the study. Positive xenodiagnosis was associated with lower lymphoblastogenic responses to T. cruzi in group 1 patients, suggesting the presence of a regulatory or modulatory mechanism which is lost in patients with chagasic cardiomyopathy. No relationship between positive xenodiagnosis and positive lymphoblastogenesis in response to heart antigen could be established. In addition, no correlation was found between clinical heart disease and reactivity to rat heart tissue.