Presence of antiheart and antiskeletal muscle glycolipid autoantibodies in the sera of patients with chagasic cardiopathy.

OBJECTIVE: To characterize biochemically and isolate the skeletal and heart muscle cell epitope recognized by the autoantibodies present in the serum of chronically infected Trypanosoma cruzi patients. Secondly, to use that epitope in an immunoenzymatic assay for determining differences in antibody titre among Chagas' and other protozoan and heart diseases and between asymptomatic and cardiopathic chagasic patients.

DESIGN: Isolated human skeletal and heart muscle cells were treated with organic solvents, pronase, neuraminidase and sodium metaperiodate before immunofluorescence assay. Glycolipids were extracted from human skeletal muscle for ELISA.

PATIENTS: Sera were collected from 155 patients with positive serology for T cruzi infection; 44 healthy blood bank donors; and from patients after heart transplantation (16 patients), during the first month after cardiac infarction (eight) or cardiotomy (10), dilated myocardiopathy (21), leishmaniasis (12), acute toxoplasmosis (four) and hyperthyroid ophthalmopathy (five).

MAIN RESULTS: Immunofluorescence assay revealed that the chagasic sera recognized epitopes that appeared to be glycolipid in nature. ELISA showed that the chagasic sera contained a higher titre of antiskeletal muscle glycolipid antibodies than the control sera and that, in the chagasic population, antibody titre was significantly higher in patients with heart failure than in asymptomatic subjects or in those presenting only electrocardiographic abnormalities.

CONCLUSIONS: The skeletal and heart muscle epitope recognized by antibodies present in the sera of chagasic patients has the characteristics of a glycolipid. ELISA with glycolipids extracted from human skeletal muscle indicated that chagasic patients presented a higher antibody titre and that patients with heart failure showed a titre significantly higher than those who were asymptomatic or with electrocardiographic abnormalities, suggesting that those antibodies could be immunological markers and even predictors of heart failure in Chagas' disease.