TNF-α pre- and posttreatment protocols for survival, histology, and apoptosis studies. (A) Pretreatment. Mice received 2.0 μg rmTNF-α at 24, 6, or 1 h before injection with either 9 μg/kg Stx1 or 10 ng/kg Stx2 at time zero. Subsequently, mice were monitored for morbidity (survival curves) or euthanized 48 h after Stx injection (histology, TUNEL staining). (B) Posttreatment. Mice received 9 μg/kg of Stx1 at time zero. One, 6, and 24 h later, mice were given 2.0 μg rmTNF-α and monitored for morbidity (survival curves) or euthanized 48 h after Stx1 injection (histology, TUNEL staining).