iLite® CD19 (-) Target Assay Ready Cells are genetically engineered human cells (Raji, ATCC# CCL-86) depleted of CD19 expression. The cells are to be use as negative controls together with iLite® CD3 Effector Assay Ready Cells and iLite® CD19 (+) Target Assay Ready Cells for measurement of bi-specific CD3-CD19 antibody activity.