In vivo protection against LeTx cytotoxicity. Percent survival of female Balb/c mice treated with 100 μg LeTx by i.p. injection followed 5 minutes later with 8 mg/kg anti-PA83 IgG or F(ab')2 antibodies in 200 μl (5 per group). Control mice (Saline, 3 in group) received 100 μg LeTx followed by 200 μl Saline. All mice were observed twice daily for signs of illness or distress and all surviving mice were euthanized at day 11 post-challenge. P < 0.03 by the logrank test.