FIGURE 3.

Sandy-1, Sandy-2, and to a lesser extent Sandy-4 inhibit activity of mouse BAFF. A, different reporter cell lines expressing the extracellular domains of BAFFR, TACI, or BCMA (or EDAR as a control) fused to the transmembrane and intracellular domains of Fas (mBAFFR:Fas, hTACI:Fas, hBCMA:Fas, hBAFFR:Fas, and hEDAR:Fas) were exposed to titrated amounts of FLAG-mouse BAFF in the presence of the indicated fixed concentrations of different anti-mBAFF or anti-EDA (EctoD3) mAbs. After 16 h of culture, cell viability was monitored with the phenazine methosulfate/3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Blocking antibodies protect reporter cells from death. B, same as A except that Fc-mouse BAFF (or Fc-EDA for EDAR:Fas reporter cells) was used to trigger death of reporter cells. Error bars represent S.E. of triplicate measures (except for EDAR:Fas, monoplicates). The experiment was performed twice (once in monoplicate) with similar results.