TNF production by chemokine stimulation. Purified peripheral blood B cells from normal donors were incubated with the indicated chemokines with or without anti-IgM monoclonal antibody (mAb) for 24 hours. The concentration of TNF in the culture supernatant was measured by ELISA. Data are mean ± standard error of the mean values of three independent experiments analyzed in duplicate. *P < 0.05, **P < 0.005, ***P < 0.0005, vs no chemokine stimulation.