Plasmacytoid dendritic cells take up opsonized antigen leading to CD4+ and CD8+ T cell activation in vivo.
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.
Björck
Pia
P
Department of Pathology/Stanford Blood Center, Division of Blood and Marrow Transplantation, Stanford University, Palo Alto, CA 94304, USA. bjorck@stanford.edu
Beilhack
Andreas
A
Herman
Edward I
EI
Negrin
Robert S
RS
Engleman
Edgar G
EG