Figure 6.

Lack of contribution of IFNβ, TNFα, IL-6 and lipopolysaccharide to survival induced by conditioned medium. (a) Recombinant IFNβ or fibroblast-conditioned medium (FCM) from rheumatoid arthritis synovial fibroblasts stimulated with TNFα and IL-17 (RASF_IL-17/TNF) were added to neutrophils in the presence or absence of an anti-CD118 (type I interferon receptor) blocking antibody (filled bars) or irrelevant control. (b) Using either irrelevant control antibodies, specific granulocyte–macrophage colony-stimulating factor (GM-CSF) and/or TNFα antibodies conjugated to agarose beads, serum-free conditioned medium (unstimulated or IL-17A/TNFα stimulated) was depleted of GM-CSF and/or TNFα and added to freshly isolated peripheral blood neutrophils for 24 hours. In some experiments, additional blockade of IFNβ receptors (CD118) and IL-6 receptors was employed after depletion steps. Error bars show the mean ± standard deviation from three independent experiments. (c) Lipopolysaccharide (10 ng/ml) or FCM from RASF_IL-17/TNF was added to neutrophils in the presence or absence of polymyxin B (50 μg/ml, filled bars). **P < 0.01, *P < 0.05; ns, nonsignificant.