BLyS induces monocyte survival. CD14⁺ monocytes were cultured ± 100 ng/mL BLyS for 24 hours before assessing CD14 expression levels by flow cytometry (A) or cell morphology (B) as revealed by forward (FSC) versus side scatter (SSC). (C) To assess the effects of BLyS on monocyte survival over time, cells were cultured ± 100 ng/mL _LBLyS for 1 to 3 days and the percentage of viable cells was determined by FITC-annexin V and PI staining. (D) Four commercial preparations of BLyS (100 ng/mL) were compared with 20 ng/mL LPS for their ability to promote monocyte survival after 3 days of culture.