title: Autoradiographical demonstration of C3b receptor activity on resident peritoneal macrophages.
abstract: The present study was performed to evaluate the usefulness of 125I-labelled C3b bound to constituents of sheep erythrocyte membranes (125I-C3b-OR) for the demonstration of C3b receptor activity of resident peritoneal macrophages at the electron-microscopical level. The binding of 125I-C3b-OR to the cells was studied in biochemical and autoradiographical experiments. The amount of cell-associated radioactivity was dependent on the presence of unlabelled aggregated C3b (AC3b) in a dose-response manner, and diminished strongly after functional inactivation of the receptor by trypsin treatment. In addition, it was found that at 4 degrees C most of the label was associated with the cell surface. However, when the incubation temperature was raised from 4 degrees C to 37 degrees C, internalization of the label was observed. These results indicate that 125I-C3b-OR is a suitable agent for further characterization of the C3b receptor-function of resident peritoneal macrophages at the electron-microscopical level.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology*; D001345:Autoradiography; D005260:Female; D006168:Guinea Pigs; D007457:Iodine Radioisotopes; D008264:Macrophages / Q000276:immunology*; D008854:Microscopy, Electron; D011951:Receptors, Complement / Q000378:metabolism*; D017463:Receptors, Complement 3b
chemical_list: D007457:Iodine Radioisotopes; D011951:Receptors, Complement; D017463:Receptors, Complement 3b