title: Demonstration of IgG-Fc and C3 receptors on adult Schistosoma mansoni.
abstract: Previous studies have indicated that adult schistosomes have an affinity for both IgG and C; however, thorough investigations on the possible presence of receptors for these serum proteins on the adult schistosome tegument have not been attempted. The present study presents evidence for both IgG-Fc and C3 receptors on adult schistosomes. An indirect assay utilizing fluoresceinated Staphylococcus aureus was developed to detect antigen-antibody (Ag-Ab) and antigen-antibody-C (Ag-Ab-C) binding to adult parasites. Detection of Ag-Ab and Ag-Ab-C complex binding was dependent on the presence of a metabolic inhibitor in the incubation mixture presumably to prevent shedding of bound complexes. Ag-Ab complex binding required the presence of an intact Fc on the IgG of the complex and could be partially inhibited by preincubation of parasites in heat-aggregated IgG or an isolated Fc preparation. Binding of Ag-Ab-C complexes was dependent on active C3 in the C source but not on an intact Fc on the IgG of the complex. Ag-Ab-C binding could be blocked by prior incubation of parasites in heat-aggregated IgG-C but not by C alone. Binding of host serum proteins to IgG-Fc and C3 receptors on adult schistosomes may aid parasite survival by helping to prevent immune detection.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D001665:Binding Sites; D002417:Cattle; D003176:Complement C3; D007074:Immunoglobulin G; D051379:Mice; D011817:Rabbits; D011951:Receptors, Complement; D011961:Receptors, Fc; D012550:Schistosoma mansoni / Q000276:immunology; D012552:Schistosomiasis / Q000276:immunology
chemical_list: D000936:Antigen-Antibody Complex; D003176:Complement C3; D007074:Immunoglobulin G; D011951:Receptors, Complement; D011961:Receptors, Fc