RT Journal Article
SR Electronic
T1 Visualizing the Site and Dynamics of IgG Salvage by the MHC Class I-Related Receptor, FcRn
JF The Journal of Immunology
JO J. Immunol.
FD American Association of Immunologists
SP 2021
OP 2029
DO 10.4049/jimmunol.172.4.2021
VO 172
IS 4
A1 Ober, Raimund J.
A1 Martinez, Cruz
A1 Vaccaro, Carlos
A1 Zhou, Jinchun
A1 Ward, E. Sally
YR 2004
UL http://www.jimmunol.org/content/172/4/2021.abstract
AB The MHC class I-related receptor, FcRn, plays a central role in regulating the serum levels of IgG. FcRn is expressed in endothelial cells, suggesting that these cells may be involved in maintaining IgG levels. We have used live cell imaging of FcRn-green fluorescent protein transfected human endothelial cells to analyze the intracellular events that control IgG homeostasis. We show that segregation of FcRn-IgG complexes from unbound IgG occurs in the sorting endosome. FcRn or FcRn-IgG complexes are gradually depleted from sorting endosomes to ultimately generate multivesicular bodies whose contents are destined for lysosomal degradation. In addition, the pathways taken by FcRn and the transferrin receptor overlap, despite distinct mechanisms of ligand uptake. The studies provide a dynamic view of the trafficking of FcRn and its ligand and have relevance to understanding how FcRn functions to maintain IgG homeostasis.