TACI-Fc induces apoptosis of primary myeloma cells. Mononuclear cells from tumor samples of 6 patients with MM were cultured for 4 days in the presence of IL-6 (1 ng/mL) with or without DEX (10^-6 M), TACI-Fc (10 ng/mL), or B-E8 (10 ng/mL). At day 4 of culture, the cell count and viability were determined and the percentage of CD138⁺ viable plasma cells was determined by flow cytometry. The power of an inhibitor is given as the percentage of reduction of the median value of viable myeloma cell count with the inhibitor compared with the median value of viable myeloma cell count without inhibitor.