FACS analysis of OA synovial cells. (a) Fluorescence-activated cell sorting (FACS) analysis of total (upper three panels) and CD14+-depleted (lower three panels) osteoarthritis (OA) cultures of synovial cells. The upper three panels show FACS analysis of forward scatter/side scatter (FSC/SSC) (left panel), analysis of FL2+ cells after incubation with the anti-CD14 phycoerythrin antibody with the CD14+ population indicated in region R2 (middle panel), and the CD14+ cells in this region showing as FL2+ in a histogram (right panel). The corresponding lower three panels show diminution of the macrophage population on FSC/SSC (left panel), disappearance of CD14+ cells (middle panel), and a histogram (right panel) after depletion of CD14+ cells. (b) A functional assay using the spontaneous tumour necrosis factor-alpha (TNF-α) production from the OA synovial cells shows effective inhibition of TNF-α production in CD14+-depleted cells from two patients (left panel), whereas CD3+ cell depletion has no effect.