Cytokine release and phenotypic changes following mDC exposure to TLR agonist. Synovial fluid (SF) myeloid dendritic cells (mDCs) mature and release tumour necrosis factor alpha (TNF-α) at comparable levels with healthy peripheral blood (PB) mDCs, but only SF mDCs release IL-10. Cytokine release and the maturation status of mDCs purified from healthy control PB (n = 3) or inflammatory arthritis SF (rheumatoid arthritis, n = 2; psoriatic arthritis, n = 1) were assessed after 24-hour incubation with granulocyte–macrophage colony-stimulating factor (GM-CSF)-supplemented media alone or containing Staphylococcus aureus peptidoglycan (PGN) (10 μg/ml). (a) The concentrations of TNF-α and IL-10 in supernatant from the cultures were determined by multiplex analysis and were expressed as release per 5 × 104 cells. Squares indicate individual donors. (b) Maturation and co-stimulation marker expression was determined by flow cytometry, and one representative example from each of the healthy control PB and inflammatory arthritis SF groups are shown.