Anti-CD19 inhibits cell growth. The number of cells (top panels) and the viability detected by trypan blue exclusion (bottom panels) are shown. Namalwa/MDR1 cells (A) and parental Namalwa cells (B) were cultured either in media (control) (•) or in the presence of 15 μg/mL of HD37 (○) and RFB4 (▾), and the number of cells was determined daily. The viability of Namalwa/MDR1 cells (C) and parental Namalwa cells (D) was also determined for cells grown in the presence of 25 nM vincristine in media only (•) or in media supplemented with 15 μg/mL of either HD37 (○) or RFB4 (▾). Viabilities of both cell lines treated with HD37 alone are also shown (▿).