title: The role of the mannose/N-acetylglucosamine receptor in the pinocytosis of horseradish peroxidase by mouse peritoneal macrophages.
abstract: Saccharomyces cerevisiae mannan inhibits the pinocytosis of horseradish peroxidase (HRP) by resident, thioglycollate-,proteose peptone-, and Corynebacterium parvum-elicited macrophages from 30 to 70% when 1 mg/ml HRP is used, and 65 to 87% when 250 micrograms/ml HRP is used. In contrast, HRP uptake by J774 cells, a macrophage cell line reported to have little mannose receptor activity, is inhibited only about 25% by mannan. HRP uptake by resident and thioglycollate-elicited (thio) macrophages is also inhibited 34 and 66% by addition of EGTA to the medium and 55 and 79% by trypsin treatment of the macrophages, respectively. The inhibitory effect of EGTA can be reversed by 1 mM excess Ca2+. High extracellular concentrations of Ca2+, in the range of 10-20 mM, however, inhibit pinocytosis in resident macrophages by about 50%. Sucrose uptake by resident macrophages is not appreciably affected by mannan. These results support the hypothesis that HRP uptake is mediated by the macrophage mannose/N-acetylglucosamine receptor. PMA stimulates fluid-phase pinocytosis of HRP by thio macrophages but does not affect receptor-mediated uptake of HRP, while the combination of adenosine, homocysteine, and erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) selectively inhibits bulk-phase uptake by thio macrophages.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D004533:Egtazic Acid / Q000494:pharmacology; D006735:Horseradish Peroxidase / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000502:physiology*; D008351:Mannans / Q000494:pharmacology; D037241:Mannose-Binding Lectins; D051379:Mice; D010873:Pinocytosis / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000502:physiology*; D011971:Receptors, Immunologic; D013395:Sucrose / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D008351:Mannans; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C035313:mannose-N-acetylglucosamine receptor; D004533:Egtazic Acid; D013395:Sucrose; D006735:Horseradish Peroxidase; D014357:Trypsin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium