Tumor necrosis factor α and IL-6 production by monocyte subsets with stimulation. Purified CD16+ and CD16- peripheral blood monocytes were incubated either with receptor activator of NF-κB ligand (RANKL) (0, 40, 200, 1000 ng/ml) or macrophage colony-stimulating factor (M-CSF) (0, 25, 125 ng/ml) for 24 hours. Tumor necrosis factor alpha (TNFα) and IL-6 concentrations in the culture supernatant were measured by ELISA. Results are representative of more than three independent experiments. Open squares, CD16+ monocytes; filled squares, CD16+ monocytes. Data are the mean ± standard error of the mean values of duplicate wells. *P < 0.03, no stimulation vs either RANKL or M-CSF stimulation; †P < 0.03, CD16+ vs the CD16- monocyte subset.