Cutting edge:: Peyer's patch plasmacytoid dendritic cells (pDCs) produce low levels of type I interferons:: Possible role for IL-10, TGFβ, and prostaglandin E2 in conditioning a unique mucosal pDC phenotype

The organized lymphoid tissues of the intestine likely play an important role in the balance between tolerance to harmless mucosal Ags and commensal bacteria and immunity to mucosal pathogens. We examined the pbenotype and function of plasmacytoid dendritic cells (pDCs) from murine Peyer'spatches (PPs). When stimulated with CpG-enriched oligodeoxynucleotides in vitro, PPs and spleen pDCs made equivalent levels of IL-12,yet PP pDCs were incapable of producing significant levels of type I IFNs. Three regulatory factors associated with mucosal tissues, PGE(2), IL-10, and TGF beta, inhibited the ability of spleen pDCs to produce type I IFN in a dose-dependent fashion. These studies suggest that mucosal factors may regulate the production of type I IFN as well as IL-12 by pDCs. In the intestine, this may be beneficial in preventing harmful innate and adaptive immune responses to commensal microorganisms.