ABSTRACT
Binding of the complement components C3 and C5 to epimastigote and trypomastigote stages of the Brazil strain of Trypanosoma cruzi was examined using radioligand binding and flow cytometric assays. Fibroblast-derived trypomastigotes bound approximately 40% fewer molecules of [125I]C3 per parasite than did epimastigotes. The predominant molecular species of C3 deposited on fibroblast-derived trypomastigotes was the inactive form iC3b. Addition of parasite-specific antisera failed to enhance the number of molecules of [125I]C3 per parasite or the proportion of active to inactive C3b. Flow cytometric studies revealed that only 50% of trypomastigotes (fibroblast-derived or blood-form) bound C3. In contrast to results of the [125I]C3 binding studies, flow cytometric analysis showed that the percentage of trypomastigotes binding C3 actually increased upon incubation with parasite-specific antisera. C5 was found also to bind to only a percentage of trypomastigotes.
Subject(s)
Complement C3/immunology , Complement C5/immunology , Trypanosoma cruzi/immunology , Animals , Autoradiography , Brazil , Densitometry , Fibroblasts/parasitology , Flow Cytometry , Fluorescein-5-isothiocyanate , Humans , Kinetics , Radioligand AssayABSTRACT
A man developed paracoccidioidomycosis with non-productive cough and changes on chest roentgenogram one year following agricultural work in Ecuador. Oropharyngeal and nasal lesions developed 2 years later. This chronic fungal infection is typically difficult to cure, and relapses are common. After treatment with 2.5 g of amphotericin B and a 3-year course of triple sulfa, our patient remained free of disease during 12 years of follow-up.