Autoantibodies to human heart conduction system in Chagas' disease

Destruction of heart tissue in chronic chagasic cardiopathy may be caused by autoimmune recognition of heart tissue. Indirect evidence suggests that there is antigenic cross-reactivity between Trypanosoma cruzi and heart tissue. The objective of this study was to determine whether seric autoantibodies against atrio-ventricular (AV) node and sinus auricular node tissues are markers of chronic cardiopathy condition. We searched for the presence of seric autoantibodies against AV node and sinus auricular node tissues in 25 sera from chronic chagasic cardiopathy patients, 20 sera from non-chagasic cardiopathy patients, 20 sera from indeterminate chagasic subjects, and 20 sera from healthy blood donors as controls. Diagnosis of dilated cardiopathy was established based on the left-ventricular end systolic dimension and cardiothoracic ratio on chest x-radiography and impaired contracting ventricle, and chagasic etiology by demonstration of circulating antibodies using ELISA and IIF. Autoantibody detection against conduction heart tissue was carried out by immunohistochemical test. The tissues were obtained from non-cardiopathy necropsy case. Human sera were diluted at 1:10 in PBS-FSB. Goat antihuman laminin was used as positive control. Autoantibodies were more frequently found in chronic chagasic cardiopathy (20%) compared to non-chagasic cardiopathy (5%) and indeterminate chagasic subjects (5%), pattern staining define interstitial and membrane targets on rich conduction system tissue. In conclusion seric autoantibodies against heart conduction system are not a good markers for chagasic cardiopathy group. Their presence showed no clear association with complex rhythm/conduction aberrations.