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IgG subclass reactivity to Trypanosoma cruzi in chronic chagasic patients
N Hernández-Becerril1, A Nava, P A Reyes
1Laboratorio de Inmunoparasitología, Instituto Nacional de Cardiología I. Chávez, INCICH, Juan Badiano No. 1, 14080 México D.F.
Background:
The anti-Trypanosoma cruzi antibodies isotype profile in Chagas' disease has been studied in relation to different clinical manifestations. A high titer of IgG anti-T. cruzi antibodies is found in patients with cardiac involvement, while a high titer of IgA anti-T. cruzi antibodies is associated with digestive forms.
Objective:
The aim of this work was to analyze the IgG subclass reactivity of anti-T. cruzi antibodies in patients with chronic Chagasic cardiomyopathy.
Methods:
Twelve consecutive chagasic patients were analyzed for IgG subclass reactivity to a T. cruzi antigenic extract. They had a complete clinical evaluation, peripheral EKG, echocardiography, left ventriculogram, and coronariography.
Results:
All patients came from rural areas of Mexico and had lived in endemic zones for over seven years. They presented left ventricular endsystolic dimension above 42 mm in 58% (7/12) and ejection fraction below 50% in 58% (7/12). We found that IgG1 and IgG2 anti-T. cruzi antibodies showed higher titer than IgG3 antibodies, with consistently low titer of IgG4 antibodies. Expression of the four IgG subclasses of anti-T. cruzi antibodies suggest a mixed Th1/Th2-like immune response under a probably continuous chronic antigenic stimulation. On the other hand, high levels of IgG2 anti-T. cruzi antibodies showed a tendency to be associated with severe cardiomegaly.
Conclusions:
Our results suggest that a mixed Th1/Th2-like immune response may take place in chronic chagasic patients under a chronic antigenic stimulation.