title: Plasmacytoid dendritic cells take up opsonized antigen leading to CD4+ and CD8+ T cell activation in vivo.
abstract: Plasmacytoid dendritic cells (pDC) are the body's main source of IFN-alpha, but, unlike classical myeloid DC (myDC), they lack phagocytic activity and are generally perceived as playing only a minor role in Ag processing and presentation. We show that murine pDC, as well as myDC, express Fcgamma receptors (CD16/CD32) and can use these receptors to acquire Ag from immune complexes (IC), resulting in the induction of robust Ag-specific CD4(+) and CD8(+) T cell responses. IC-loaded pDC stimulate CD4(+) T cells to proliferate and secrete a mixture of IL-4 and IFN-gamma, and they induce CD8(+) T cells to secrete IL-10 as well as IFN-gamma. In contrast, IC-loaded myDC induce both CD4(+) and CD8(+) T cells to secrete mainly IFN-gamma. These results indicate that pDC can shape an immune response by acquiring and processing opsonized Ag, leading to a predominantly Th2 response.
authors.affiliation: Department of Pathology/Stanford Blood Center, Division of Blood and Marrow Transplantation, Stanford University, Palo Alto, CA 94304, USA. bjorck@stanford.edu
authors.forename: Pia
authors.initials: P
authors.lastname: Björck
authors.forename: Andreas
authors.initials: A
authors.lastname: Beilhack
authors.forename: Edward I
authors.initials: EI
authors.lastname: Herman
authors.forename: Robert S
authors.initials: RS
authors.lastname: Negrin
authors.forename: Edgar G
authors.initials: EG
authors.lastname: Engleman