Figure 5.
No detectable effector function of belimumab bound to membrane-bound BAFF. (A) CHO BAFF Δstalk cells or CHO cells were pre-incubated for 30 min with atacicept, belimumab, denosumab, adalimumab, BCMA-Fc or size-fractionated (dimeric) BCMA-Fc at the indicated concentrations, and subsequently exposed for 2 h to normal human serum that had been heat-inactivated or not. Cells viability was monitored with the PMS/MTS assay. Mean ± SEM of duplicates. Experiment performed twice (but only once for the condition of dimeric BCMA-Fc). (B) CHO BAFF Δstalk cells were pre-incubated with atacicept, belimumab, BCMA-Fc, or adalimumab at the indicated concentrations, after which time surrogate effector cells of antibody-dependent cellular-mediated cytotoxicity were added. NFAT-driven luciferase expression is induced when opsonized IgG-containing molecules engage FcγRIIIa expressed in these reporter cells. Specific signal in relative luminescence units (RLU) was obtained after subtraction of background of unstimulated cells (~105 RLU). Mean ± SEM of triplicate measures. Experiment performed twice.