Dependence of antibody-mediated presentation of antigen on FcRn.

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Antigen-Presentation, Antigen-Antibody-Complex, Antigen-Presenting-Cells, Cell-Proliferation, Dendritic-Cells, Hematopoietic-System, Hemocyanin, Histocompatibility-Antigens-Class-I, Humans, Immunoglobulin-G, Ligands, Lysosome-Associated-Membrane-Glycoproteins, Lysosomes, Mice, Monocytes, Mutation, Protein-Binding, Protein-Processing-Post-Translational, Protein-Transport, Receptors-Fc, T-Lymphocytes

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Proc Natl Acad Sci U S A 2008 Jul; 105(27):9337-42.


The neonatal Fc receptor for IgG (FcRn) is a distant member of the MHC class I protein family. It binds IgG and albumin in a pH-dependent manner and protects these from catabolism by diverting them from a degradative fate in lysosomes. In addition, FcRn-mediated IgG transport across epithelial barriers is responsible for the transmission of IgG from mother to infant and can also enhance IgG-mediated antigen uptake across mucosal epithelia. We now show a previously undescribed role for FcRn in mediating the presentation of antigens by dendritic cells when antigens are present as a complex with antibody by uniquely directing multimeric immune complexes, but not monomeric IgG, to lysosomes.