title: Binding of complement to trypomastigotes of a Brazil strain of Trypanosoma cruzi: evidence for heterogeneity within the strain.
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.
authors.affiliation: Department of Biology, Wake Forest University, Winston-Salem, North Carolina 27109.
authors.forename: K C
authors.initials: KC
authors.lastname: Jacobson
authors.forename: R G
authors.initials: RG
authors.lastname: Washburn
authors.forename: R E
authors.initials: RE
authors.lastname: Kuhn
mesh_terms: D000818:Animals; D001345:Autoradiography; D001938:Brazil; D003176:Complement C3 / Q000276:immunology*; D003182:Complement C5 / Q000276:immunology*; D003720:Densitometry; D005347:Fibroblasts / Q000469:parasitology; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D006801:Humans; D007700:Kinetics; D011869:Radioligand Assay; D014349:Trypanosoma cruzi / Q000276:immunology*
chemical_list: D003176:Complement C3; D003182:Complement C5; D016650:Fluorescein-5-isothiocyanate