Anti-Trypanosoma cruzi immunoglobulin G1 can be a useful tool for diagnosis and prognosis of human Chagas' disease

Two functionally distinct antibodies, categorized as conventional serology antibodies (CSA) and lytic antibodies (LA) have been described in Chagas' d isease, based on their ability to bind to fixed epimastigotes (EPI) or live trypomastigotes (TRYPO), respectively. In this study, the profile of immun oglobulin G (IgG) subclasses of CSA and LA were analyzed by flow cytometry using serum samples from chronic chagasic patients with the indeterminate ( IND), cardiac (CARD), and digestive (DIG) clinical forms of the disease, Th e results were expressed as percentage of positive fluorescent parasites (P PFP) for each sample. CSA showed a higher PPFP than LA for all samples. At serum dilutions between 1:256 and 1:2,048, IgG1 anti-EPI was able to distin guish chagasic from nonchagasic individuals, Different profiles of IgG subc lasses were observed for CSA and LA. IgG1 and IgG2 were the main subclasses in CSA, whereas Igc1 and IgG3 were the predominant ones in Lk The reactivi ty of IgG2 anti-EPI was greater in IND and CARD than in DIG patients. Furth ermore, a low level of IgG1 and IgG3 LA was associated with most of the CAR D patients. On the other hand, a high level of IgG1 LA was associated with most of the IND patients. In summary, our findings indicate the potential o f IgG1 anti-EPI for serological diagnosis of Chagas' disease, providing fur ther evidence for a protective role of LA, and show that IgG1 anti-live Try panosoma cruzi TRYPO may be used to predict the risk of cardiac damage in C hagas' disease.