Murine Plasmacytoid Pre-Dendritic Cells Generated from Flt3 Ligand-Supplemented Bone Marrow Cultures Are Immature APCs

Abstract

The putative counterparts of human plasmacytoid pre-dendritic cells (pDCs) have been described in vivo in mouse models and very recently in an in vitro culture system. In this study, we report that large numbers of bone marrow-derived murine CD11c+B220+ pDCs can be generated with Flt3 ligand (FL) as the sole exogenous differentiation/growth factor and that pDC generation is regulated in vivo by FL because FL-deficient mice showed a major reduction in splenic pDC numbers. We extensively analyzed bone marrow-derived CD11c+B220+ pDCs and described their immature APC phenotype based on MHC class II, activation markers, and chemokine receptor level of expression. CD11c+B220+ pDCs showed a nonoverlapping Toll-like receptor pattern of expression distinct from that of classical CD11c+B220− dendritic cells and were poor T cell stimulators. Stimulation of CD11c+B220+ pDCs with oligodeoxynucleotides containing certain CpG motifs plus CD40 ligand plus GM-CSF led to increased MHC class II, CD80, CD86, and CD8α expression levels, to a switch in chemokine receptor expression that affected their migration, to IFN-α and IL-12 secretion, and to the acquisition of priming capacities for both CD4+ and CD8+ OVA-specific TCR-transgenic naive T cells. Thus, the in vitro generation of murine pDCs may serve as a useful tool to further investigate pDC biology as well as the potential role of these cells in viral immunity and other settings.

Enhanced Production of IL-10 by Dendritic Cells Deficient in CIITA

“…Differences in B220 expression by DC may indicate some differences in developmental origin caused by CIITA deficiency. Plasmacytoid DC express increased IFN-␣ and decreased IL-12; they are also poor T cell activators (30,(37)(38)(39). It is not clear whether the change in this population in CIITA Ϫ/Ϫ DC is related to aberrant cytokine expression, or represents an alteration in DC development.…”

Critical roles of interferon regulatory factor 4 in CD11bhighCD8α–dendritic cell development

“…We next used the Flt3L-supplemented BM culture system, which can give rise to B220 Ϫ CD11c ϩ conventional DCs and B220 ϩ CD11c ϩ plasmacytoid DCs (42,43). It is demonstrated that the conventional DCs from the culture contain two types of subsets, CD11b high and CD11b low DCs (10), and the plasmacytoid DCs do not express CD11b (42,43). The number of B220 Ϫ CD11c ϩ conventional DCs developed from IRF-4 Ϫ/Ϫ BM was reduced to Ϸ60% of that produced by wild-type BM (Fig.…”

STAT3 in immune responses and inflammatory bowel diseases

“…DC differentiation from hematopoietic precursors has been extensively examined using in vitro systems. DC progeny generated in vitro by GM-CSF or Flt3L are now well defined: DC derived from GM-CSF-supplemented cultures express cell surface antigens typically associated with CD11c+ CD11b+, or called "myeloid" DC [75], while DC derived from Flt3L-supplemented cultures exhibit characteristics typically associated with plasmacytoid CD11c+ CD11b-DC (pDC) [76,77]. In my laboratory we have used this approach and directly compared the activity of Flt3L versus GM-CSF on DC differentiation in the absence of STAT3 and we will continue this line of investigation.…”