Effect of 5E6 F(ab′)2 on mice injected with a lethal dose of C1498.
5E6 F(ab′)2 treatment of mice injected with a lethal dose of C1498 results in increased survival rate. (A) B6 mice were treated with 180 μg 5E6 F(ab′)2 or 5% NMS (ip) 2 days prior to injection with 1 × 105 C1498 cells (iv). The animals were then treated with 180 μg 5E6 F(ab′)2 per dose or NMS twice a week for 3 weeks and monitored for survival. Pooled data from 2 independent experiments (n = 15 and 12 for NMS and 5E6 F(ab′)2 groups, respectively) is shown. (B) IL-2–activated NK cells (12 × 106) were preincubated with 300 μg 5E6 F(ab′)2 or 5% NMS for 2 hours at 37°C and were further cocultured with 1.2 × 106 C1498 leukemia cells for 24 hours. As controls, 1.2 × 106 C1498 cells were cultured alone. After the coculture, cells were washed and mice were injected with 1 × 105 C1498 and 1 × 106 NK cells per mouse (iv), a dose based on the cell concentration at the initiation of coculture (n = 8 per group). A representative of 3 independent experiments is shown. (C) B6 mice were injected with cocultured NK and C1498 cell mixture as in panel B. In addition, a group of mice were injected with NK and C1498 cell mixture that was cocultured in the presence of 300 μg 4D11 F(ab′)2. At days 18 and 25 post–initial tumor plus NK cell injection (indicated by arrows), mice in the appropriate group were injected with NK cells treated with NMS or 5E6 or 4D11 F(ab′)2(5 × 106 per mouse, iv) followed by IL-2 injection (5 × 104 IU per mouse, ip) of all mice for 3 consecutive days. Pooled data from 2 independent experiments (n = 20 per group except for 4D11 F(ab′)2–treated group in which n = 10) are shown. The P value indicates a significant difference between groups injected with NK cells treated with 5E6 or 4D11 F(ab′)2 as determined by log-rank test.
