title: Exposure of macrophages to an enzymatically inactive macrophage mannose receptor ligand augments killing of Candida albicans.
abstract: Macrophages (Mphi) are involved in host defenses against opportunistic pathogens. Previous studies by the present investigators indicate that Mphi exposed to enzymatically active myeloperoxidase (MPO), exhibited both increased phagocytosis and killing of Candida albicans. The purpose of this study was to determine if enzymatically inactive Mphi-mannose receptor (MMR) ligands could function similarly. Resident murine peritoneal Mphi were exposed to the MMR ligands, mannosylated bovine serum albumin (mBSA), and enzymatically inactive myeloperoxidase (iMPO), followed by exposure to opsonized C. albicans. Both mBSA and iMPO induced a slight increase in the number of phagocytizing cells; however, candidacidal activity was significantly higher in treated cultures compared to controls (P < or = 0.001). The production of reactive oxygen intermediates (ROI) was detected using chemiluminescence. After employment of ROI scavengers, a decrease in candidacidal activity was observed. The data suggest that MMR-ligand interaction alone is sufficient to significantly enhance the candidacidal activity of Mphi via ROI, and that iMPO which is released at a site of inflammation induces Mphi-mediated killing of microorganisms. These findings indicate a previously unrecognized role of iMPO.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock 79409, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Gelderman
authors.forename: D L
authors.initials: DL
authors.lastname: Lefkowitz
authors.forename: S S
authors.initials: SS
authors.lastname: Lefkowitz
authors.forename: A
authors.initials: A
authors.lastname: Bollen
authors.forename: N
authors.initials: N
authors.lastname: Moguilevsky
mesh_terms: D000818:Animals; D002176:Candida albicans; D002417:Cattle; D002478:Cells, Cultured; D005260:Female; D037181:Lectins, C-Type; D008024:Ligands; D008163:Luminescent Measurements; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology*; D008297:Male; D008358:Mannose / Q000494:pharmacology*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D051379:Mice; D008810:Mice, Inbred C57BL; D009195:Peroxidase / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D012709:Serum Albumin / Q000494:pharmacology*; D012710:Serum Albumin, Bovine / Q000494:pharmacology
chemical_list: D037181:Lectins, C-Type; D008024:Ligands; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D012709:Serum Albumin; C023840:mannose-bovine serum albumin conjugate; D012710:Serum Albumin, Bovine; D009195:Peroxidase; D008358:Mannose