FIGURE 3.

Effect of XOMA 052 on activity of IL-1β in cell-based activity assays. a, XOMA 052 neutralizes IL-1β stimulation of IL-6 release by MRC-5 cells with an IC₅₀ of ∼2 pm at the EC₅₀ for this assay (100 pg/ml IL-1β). This activity is comparable with that of control Blocking Ab 6, with an IC₅₀ of ∼6 pm. b, XOMA 052 attenuates the dose response of MRC-5 cells to IL-1β ∼50-fold (EC₅₀ values of 12 and 815 pm with an anti-KLH antibody and XOMA 052, respectively), whereas Blocking Ab 6 almost completely inhibits IL-1β activity. c, XOMA 052 neutralizes IL-1β stimulation of NFκB activation in HeLa cells stably expressing an NFκB-luciferase reporter construct with an IC₅₀ of ∼1 pm at the EC₅₀ for this assay (25 pg/ml IL-1β). Under these conditions, the potency of the control blocking antibody is 36-fold lower, with an IC₅₀ of 36 pm. RLU, relative light units. d, XOMA 052 attenuates the dose response of HeLa cells stably expressing an NFκB-luciferase reporter construct to IL-1β stimulation ∼20-fold, from an EC₅₀ of 1.7 pm in the presence of a non-binding anti-KLH antibody to 36 pm with XOMA 052. For a, c, and d, error bars show S.D. of three replicates for test samples and duplicates for the anti-KLH antibody control. For b, error bars show S.D. between duplicate samples. All experiments were run at an n = 2.