CD19xCD3 DART molecule mediates enhanced redirected killing of B-cell lymphoma. CD19⁺ cells (Raji or Daudi) or CD19⁻ cells (RPMI-8226 or K562) were seeded in 96-well plates. Human resting PBMCs (A-C) or IL-2–activated PBMCs (D-F) and serial dilutions of the CD19-CD3 DART molecule (●) or the CD19-CD3 BiTE molecule (▾) were added to the plate and incubated overnight. Cytotoxicity was then detected by LDH release. EC₅₀ values and maximum lysis were determined using GraphPad Prism software. The data are representative of multiple independent experiments using independent human PBMC donors.