Identification and characterization of major histocompatibility complex class II compartments in cortical thymic epithelial cells

Yamini Arudchelvan, Yukio Nishimura, Nobuko Tokuda, Tomoo Sawada, Yoshiya Ueyama, Tetsuo Fukumoto

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Previous studies have concentrated on elucidating the subcellular localization of major histocompatibility (MHC) class II molecules mainly in B cells, macrophages, and dendritic cells. Despite very rich cell-surface expression of MHC class II molecules by cortical thymic epithelial cells (cTECs), little is known regarding the expression of these molecules by cTECs at the subcellular level. In the present study we focused on the identification and characterization of MHC class II compartments (MIICs) in cTECs in situ by immunogold electron microscopy (Iem). We found that MHC class II molecules were located exclusively in the cytoplasmic vacuoles, and we identified these MHC class II molecule-containing cytoplasmic vacuoles as MIICs in cTECs. These MIICs were immunopositive for early endosomal, late endosomal, and lysosomal markers. Moreover, in these MIICs, MHC class II molecules were colocalized with cathepsin L, H2-DM, class II-associated invariant chain (Ii), and class II-associated invariant chain peptide (CLIP). Similarly, Ii molecules were colocalized with endosomal and lysosomal markers, cathepsin L, and H2-DM in the vacuoles. Taken together, these results suggest that MIICs in cTECs represent conventional endocytic compartments. The colocalization of MHC class II molecule or Ii with cathepsin L and H2-DM in the MIICs suggests that MIICs in cTECs may be sites of Ii degradation and peptide loading.

Original languageEnglish
Pages (from-to)798-806
Number of pages9
JournalAnatomical Record - Part A Discoveries in Molecular, Cellular, and Evolutionary Biology
Volume274
Issue number1
DOIs
Publication statusPublished - Sep 1 2003

All Science Journal Classification (ASJC) codes

  • Anatomy
  • Agricultural and Biological Sciences (miscellaneous)

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