BLyS promotes survival of NHL. Cell isolated from NHL tumors were washed and cultured in triplicate in a 96-well plate (0.1 × 10⁶ cells/well) in phenol red-free RPMI supplemented with 10% FCS alone or with the addition of 0.5 μg/mL Flag-BLyS at 37° C. After 48 hours of incubation, cells were assayed for viability with the LIVE/DEAD Viability/Cytotoxicity kit as described in “Patients, materials, and methods.” In all cases the fluorescence of a media-alone control was subtracted for the experimental value. Cell viability in the presence of BLyS was normalized to the media-alone control and is shown as relative viability.