APC and influenza: To determine the effect of APC on the procoagulant response in severe influenza, we infected mice with a lethal dose of influenza A virus and initiated rm-APC (or buffer control) treatment 24 hours after infection; subsequently, we determined the levels of TATc and FDP in lung homogenates (Figure 1A, B) and plasma (Figure 1C, D) at 48 and 96 hours after infection.