A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Tracing uptake of C3dg-conjugated antigen into B cells via complement receptor type 2 (CR2, CD21)
Tekijät: Hess MW, Schwendinger MG, Eskelinen EL, Pfaller K, Pavelka M, Dierich MP, Prodinger WM
Kustantaja: AMER SOC HEMATOLOGY
Julkaisuvuosi: 2000
Journal: Blood
Tietokannassa oleva lehden nimi: BLOOD
Lehden akronyymi: BLOOD
Vuosikerta: 95
Numero: 8
Aloitussivu: 2617
Lopetussivu: 2623
Sivujen määrä: 7
ISSN: 0006-4971
DOI: https://doi.org/10.1182/blood.V95.8.2617.008k20_2617_2623
Tiivistelmä
Electron microscopy was used to study the internalization and delivery of ligands for complement receptor type 2 (CR2, CD21) to endocytic compartments of B-lymphoblastoid Raji cells. Opsonized antigen was mimicked with purified C3dg conjugated to colloidal gold. C3dg-gold bound specifically to the cell surface in a time-dependent manner, and preincubation of the cells with a monoclonal antibody blocking the CR2 ligand-binding site completely inhibited any C3dg-gold binding. Notably, the binding of C3d-gold was confined to cell surface protrusions, eg, microvilli. C3dg-gold was apparently internalized through coated pits located at the bases of microvilli and could be traced to different compartments of the endocytic pathway. The morphologic characteristics and intracellular distribution of these multivesicular or multilaminar structures were compatible with those of compartments known to harbor major histocompatibility complex (MHC) class II molecules. Immunolabeling showed that the internalized C3dg-gold colocalized with MHC class II in these structures. These data provide the first ultrastructural evidence that complement-coated antigens are endocytosed by antigen-nonspecific B cells by CR2 and are delivered to the compartments in which peptide loading for antigen presentation occurs. They support the notion that CR2 may play a role in antigen presentation by B cells regardless of B-cell receptor specificity. (Blood, 2000;95:2617-2623) (C) 2000 by The American Society of Hematology.
Electron microscopy was used to study the internalization and delivery of ligands for complement receptor type 2 (CR2, CD21) to endocytic compartments of B-lymphoblastoid Raji cells. Opsonized antigen was mimicked with purified C3dg conjugated to colloidal gold. C3dg-gold bound specifically to the cell surface in a time-dependent manner, and preincubation of the cells with a monoclonal antibody blocking the CR2 ligand-binding site completely inhibited any C3dg-gold binding. Notably, the binding of C3d-gold was confined to cell surface protrusions, eg, microvilli. C3dg-gold was apparently internalized through coated pits located at the bases of microvilli and could be traced to different compartments of the endocytic pathway. The morphologic characteristics and intracellular distribution of these multivesicular or multilaminar structures were compatible with those of compartments known to harbor major histocompatibility complex (MHC) class II molecules. Immunolabeling showed that the internalized C3dg-gold colocalized with MHC class II in these structures. These data provide the first ultrastructural evidence that complement-coated antigens are endocytosed by antigen-nonspecific B cells by CR2 and are delivered to the compartments in which peptide loading for antigen presentation occurs. They support the notion that CR2 may play a role in antigen presentation by B cells regardless of B-cell receptor specificity. (Blood, 2000;95:2617-2623) (C) 2000 by The American Society of Hematology.
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