title: Effect of acidic extracellular pH on the receptor-mediated endocytosis of peroxidase-antiperoxidase (PAP) immune complex in rat peritoneal macrophages.
abstract: The effect of acidic extracellular medium on the uptake of peroxidase-antiperoxidase (PAP) immune complex in rat peritoneal macrophages was studied with the electron microscope. The acidic extracellular medium resulted in acidification of the cytosol in a relatively short period of time as was shown with 5(6) carboxyfluorescein as indicator. At pH 5.5 PAP was internalized. Some of the ligand was found in endosomes; however, a considerable quantity was still present at the cell surface after 5 min internalization. By 30 min the surface was cleared of PAP and the ligand was detectable almost exclusively in endosomes. PAP was never found in lysosomes which were identified by previous loading with cationized ferritin. We conclude that a pH shift of the cytoplasm results in inhibition of endosome-lysosome fusion.
authors.affiliation: 2nd Department of Anatomy, Semmelweis University of Medicine, Budapest, Hungary.
authors.forename: A L
authors.initials: AL
authors.lastname: Kiss
authors.forename: P
authors.initials: P
authors.lastname: Rohlich
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex / Q000378:metabolism* / Q000502:physiology; D003600:Cytosol / Q000378:metabolism / Q000648:ultrastructure; D004705:Endocytosis / Q000502:physiology*; D005260:Female; D005293:Ferritins; D005452:Fluoresceins; D006863:Hydrogen-Ion Concentration; D007124:Immunoenzyme Techniques; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D015388:Organelles / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D010529:Peritoneal Cavity / Q000166:cytology*; D010544:Peroxidases / Q000276:immunology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000936:Antigen-Antibody Complex; D005452:Fluoresceins; D005293:Ferritins; D010544:Peroxidases