Differential cytokine production via TLR9 in human tonsillar plasmacytoid dendritic cells

Abstract

Plasmacytoid dendritic cells (PDCs) have immunoregulatory roles, linking innate with adaptive immunity. In the present study, we investigated the characteris tics and the function of tonsillar PDC. PDCs were isolated from human tonsils and analysed by flow cytometry. The expression of toll-like receptors (TLRs) mRNA was also analyzed by RT-PCR. In addition, PDCs were stimulated in vitro with CpG DNA, and cytokine production in PDCs was determined by ELISA. The result showed the characteristics of tonsillar PDCs, which were Lin-, CD4⁺, CD11c^-, CD40⁺, CD123⁺, HLA-DRmod, CD80^-, CD86^-, CD83⁺. The expressions of TLR7 and TLR9 mRNA were detected in PDCs. Differential cytokine production via TLR9 signaling was observed in PDCs. A type CpG, CpG2216 induced IFN-a production, whereas B type CpG, CpG2006 and co-stimulation with anti-CD40 antibody induced IL-12 production in tonsillar PDCs. These findings indicate that PDCs might play an important role as a link between innate and adaptive immunity in the tonsil.