Human antibodies against Trypanosoma cruzi exoantigens recognizing parasite surface antigens and heart tissue components.

This work describes the occurrence of antibodies against exoantigens of Trypanosoma cruzi in a high percentage of patients with chronic Chagas' disease. When analyzing selected groups of patients, it was observed that sera from individuals with electrocardiographic alterations showed a greater number of precipitin system and higher antibody titers than sera from patients with positive serology only. Partial characterization of exoantigens of T. cruzi was performed by isoelectric focusing and immunoblotting. Two distinct groups of antigens at pI around 5 and 6, respectively, were identified by these methods. It was also shown in absorption experiments that exoantigens of lower pI share epitopes with components of the cellular surface of epimastigotes of T. cruzi, whereas exoantigens of higher pI share epitopes with normal human heart tissue.