Enumeration of dendritic cell subsets in various arthritides and healthy volunteers. Plasmacytoid dendritic cells (pDCs) and myeloid dendritic cells (mDCs) are significantly decreased in rheumatoid arthritis (RA) peripheral blood (PB), and pDCs are significantly decreased in psoriatic arthritis (PsA) PB. The total number of (a) mDCs and (c) pDCs per millilitre of PB and the percentage of (b) mDCs and (d) pDCs of white blood cells (WBC) in healthy subjects (n = 12), RA subjects (n = 12), PsA subjects (n = 13) and osteoarthritis (OA) subjects (n = 11). Squares indicate individual samples. -, median. *P < 0.05, **P < 0.01.