NAC treatment does not resolve TTP signs in the preclinical baboon model. (A) Anti-ADAMTS13 antibody 3H9 was injected on days 0, 2, 4, and 6, directly after blood withdrawal. NAC (400 mg/kg) treatment was initiated (large arrow) after blood withdrawal on day 3 and continued twice daily at 12-hour intervals up to day 8 (n = 4; open blue circles). Control baboons were injected with equal volumes of saline (n = 4; solid red circles). (B-C) Platelet count (B) and hemoglobin level (C) were determined daily. (D) Blood smears were made, and the number of schistocytes as a percentage of total red blood cells was counted manually. (E) LDH activity levels were determined. (F) Representative image of the VWF multimers in blood taken from control baboons and NAC-treated baboons on day 7. (G) Densitometric analysis was performed, and the two traces from the VWF multimers in panel F are shown. (H) Using densitometric analysis, the percentage of HMW VWF multimers was quantified for control baboons and NAC-treated baboons. Graphs represent the mean and standard deviation. Statistical significance is indicated with an asterisk: *P < .05.