Ho et al. tested the capability of CD8α+ DCs, CD8α- DCs, plasmacytoid dendritic cells (pDCs), and macrophages to store and present antigen delivered in vivo to C57BL/6 mice as OVA antigen/IgG antibody complexes. CD8α+ DCs were most efficient at MHC-I cross-presentation and induction of cytotoxic CD8+ T cells and demonstrated prolonged (≥ 1 week) antigen storage. Only CD8α- DCs were capable of prolonged MHC-II presentation to CD4+ T cells. Neither pDCs or macrophages were capable of protein antigen presentation.

An exclusive feature of dendritic cells (DCs) is their ability to cross-present exogenous antigens in MHC class I molecules. We analyzed the fate of protein antigen in antigen presenting cell (APC) subsets after uptake of naturally formed antigen-antibody complexes in vivo. We observed that murine splenic DC subsets were able to present antigen in vivo for at least a week. After ex vivo isolation of four APC subsets, the presence of antigen in the storage compartments was visualized by confocal microscopy. Although all APC subsets stored antigen for many days, their ability and kinetics in antigen presentation was remarkably different. CD8alpha(+) DCs showed sustained MHC class I-peptide specific CD8(+) T cell activation for more than 4 days. CD8alpha(-) DCs also presented antigenic peptides in MHC class I but presentation decreased after 48 h. In contrast, only the CD8alpha(-) DCs were able to present antigen in MHC class II to specific CD4(+) T cells. Plasmacytoid DCs and macrophages were unable to activate any of the two T cell types despite detectable antigen uptake. These results indicate that naturally occurring DC subsets have functional antigen storage capacity for prolonged T cell activation and have distinct roles in antigen presentation to specific T cells in vivo. This article is protected by copyright. All rights reserved.

Author Info: (1) Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. (2) Department of Immunohematology and Blood Transfusion, Leiden University Medical Center

Author Info: (1) Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. (2) Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. (3) Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. (4) Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.

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