Plasmacytoid dendritic cells (pDCs) are critical in controlling adaptive immunity, but the mechanisms governing cytokine expression remain incompletely defined. Analogues of prostaglandin (PG)I 2 , such as iloprost, can modulate functions of myeloid dendritic cells, but their involvement in the regulation of human pDCs remains unknown. To this end, the regulatory role of PGI 2 analogues on cytokine expression in pDCs was investigated.Circulating pDCs were magnetically sorted with BDCA-4 cell isolation kits from human peripheral blood mononuclear cells and treated with varying concentrations of iloprost with or without the addition of Toll-like receptor agonists, or an I prostanoid (IP) receptor antagonist, CAY10449. The levels of tumour necrosis factor (TNF)-a, interferon (IFN)-a and interleukin (IL)-10 were measured by ELISA.Iloprost induced IL-10 expression, but suppressed CpG oligodeoxynucleotide-(or imiquimod-) induced TNF-a and IFN-a production in pDCs. This effect was reversed by the addition of CAY10449. Forskolin, a cyclic adenosine monophosphate activator, conferred a similar modulating effect to that noted in iloprost-treated pDCs, although a higher concentration of forskolin was required to exert the same effect.Iloprost enhanced interleukin-10 and suppressed Toll-like receptor-mediated tumour necrosis factor-a and interferon-a production of human plasmacytoid dendritic cells via the I prostanoid receptor and, in part, the cyclic adenosine monophosphate pathway.

Polyclonal B-cell activation is the central theme in the production of autoantibodies and possible activation of autoreactive T cells in both human and murine lupus. The abnormal expansion of CD5 þ B cells in murine lupus has been suggested, in particular, to be one of the most characteristic findings in these mice. Activated B cells can be separated from the B cells of resting stage by the difference in cell density. The aim of this study was to investigate the characteristics of different densities of the spleen cells separated by gradient density. Furthermore, the ability of anti-DNA antibody secretion in each percoll gradient fraction of B cells was also analysed. The results showed: a higher percentage of CD5 þ B cells, which corresponded to the activated Bcell population, in percoll gradient 1 and 2 fractions; that splenic B cells of NZB/W F 1 mice had proliferative response to interleukin (IL)-4 or IL-5 but not to IL-10 or interferon-g (IFN-g); and that B cells isolated by percoll gradient produced anti-DNA antibody after stimulation with lipopolysaccharide (LPS) plus IL-5 and IFN-g, but not IL-4 and IL-10. These data suggest that B cells at different stages of activation express differential characteristics and functions.