Preferential killing of NHL cells over normal B cells. (A) The effect of the indicated mAbs on peripheral blood lymphocytes from healthy volunteers was evaluated in vitro using flow cytometry. Decrease in the percentage of CD19⁺ (B cells) and CD3⁺ (T cells) present in the lymphocyte gate after a 2-day incubation of heparinized whole blood of a healthy volunteer with various mAbs. Error bars represent SD. (B) The effects of the indicated mAbs on peripheral blood B cells and Daudi (top) or Raji (bottom) lymphoma cells are indicated as the number of CD19⁺ events relative to untreated cell mixtures. B cells are derived as the CD19⁺ cells in the lymphocyte gate, whereas Daudi and Raji cells are located in the monocytes gate.