Fig. 1

Timeline of experimental interventions, measurements, and treatments as described in the “Methods” section. At time 0 (T0), all animals were started on a continuous 24-h infusion of lethal toxin (LT) and edema toxin (ET) together. The animals were randomly assigned to receive intravenous immune globulin (IVIG) as control or anthrax immune globulin (AIG) at T-4 or T2 in six weekly experiments, at T2 or T5 in one experiment, and at T5 in one experiment. To prevent hypersensitivity reactions in the animals, infusions of AIG or IVIG were administered in gradually increasing concentrations such that the first 50% of the total dose was given over 4 h and then the second 50% over 2 h and 20 min, starting from the designated treatment time (see Additional file 1: Table S1). Hemodynamic support included a single bolus of 20 mL/kg of normal saline if the pulmonary capillary wedge pressure (PCWP, checked every 2 h for the first 8 h and every 4 h thereafter) was < 10 mmHg. Also, if at any time the mean arterial pressure (MAP) decreased to < 80 mmHg for > 5 min, a norepinephrine (NE) infusion was initiated at 0.2 μg/kg/min and if necessary increased in stepwise fashion every 5 min to 0.6, 1, or a maximum of 2 μg/kg/min. NE was titrated down in a stepwise fashion if MAP was > 100 mmHg for 5 min. Abbreviations: ABG, arterial blood gas; CBC, complete blood count; CVP, central venous pressure; HR, heart rate; LVEF, left ventricular ejection fraction (measured with echocardiography); PAS and PAD, pulmonary systolic and diastolic pressures respectively