Efficient uptake of mannosylated proteins by a human Schwann cell line

Histol Histopathol. 2009 Aug;24(8):1029-34. doi: 10.14670/HH-24.1029.

Abstract

Complex carbohydrate structures are essential molecules of infectious microbes and host cells, and are involved in cell signaling associated with inflammatory and immune responses. The uptake of mannose-tailed glycans is usually carried out by macrophages, dendritic cells (DCs), and other professional phagocytes to trigger MHC class I- and MHC class II-restricted antigen presentation, and to promote T cell effector responses. Since Schwann cells (SCs) have been proposed as immunocompetent cells, we investigated whether a human cell line (ST88-14 cells) could bind mannosylated ligands in a specific manner. The saturation of uptake of mannosylated molecules by ST88-14 cells and the internalization and distribution pathway of these ligands were tested by cytometry and confocal plus electron microscopy, respectively. This uptake showed a dose-dependent increase, the saturation point being reached at high concentrations of mannosyl residues/240 mM mannose. Merging of man/BSA-FITC and S100 labeling showed their partial, but, significant colocalization. Ultrastructural analysis of ST88-14 cells after incubation with HRP-colloidal gold, without or with subsequent chasing at 37C, showed an initial location on the cell surface and temperature- and time-dependent internalization of the probe. Our findings suggest an efficient mannosylated ligand uptake system through putative lectin(s) that may be operational in inflammatory and immune responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Endocytosis / immunology
  • Fluorescein-5-isothiocyanate / metabolism
  • Fluorescent Dyes / metabolism
  • Gold / metabolism
  • Horseradish Peroxidase / metabolism
  • Horseradish Peroxidase / ultrastructure
  • Humans
  • Immunohistochemistry
  • Lectins, C-Type / metabolism
  • Lectins, C-Type / ultrastructure
  • Ligands
  • Mannose / metabolism*
  • Mannose Receptor
  • Mannose-Binding Lectins / metabolism
  • Mannose-Binding Lectins / ultrastructure
  • Receptors, Cell Surface / metabolism
  • Receptors, Cell Surface / ultrastructure
  • S100 Proteins / metabolism
  • Schwann Cells / metabolism*
  • Schwann Cells / ultrastructure

Substances

  • Fluorescent Dyes
  • Lectins, C-Type
  • Ligands
  • Mannose Receptor
  • Mannose-Binding Lectins
  • Receptors, Cell Surface
  • S100 Proteins
  • Gold
  • Horseradish Peroxidase
  • Fluorescein-5-isothiocyanate
  • Mannose