Acute lung injury is a principal cause of morbidity and mortality in response to
mustard gas (SM) inhalation. Obstructive,
fibrin-containing airway casts have recently been reported in a rat inhalation model employing the SM analog
2-chloroethyl ethyl sulfide (
CEES). The present study was designed to identify the mechanism(s) causing activation of the coagulation cascade after
CEES-induced airway injury. Here we report that
CEES inhalation elevates
tissue factor (TF) activity and numbers of detached epithelial cells present in lavage fluid (BALF) from rats after exposure (18 h). In vitro studies using 16HBE cells, or with rat BALF, indicated that detached epithelial cells could convert
factor X (FX) to the active form FXa when incubated with
factor VII and could elicit rapid clotting of plasma. In addition, immunocytochemical analysis demonstrated elevated cell surface (TF) expression on
CEES-exposed 16HBE cells as a function of time. However, total cell TF expression did not increase. Since membrane surfaces bearing TF are important determinants of clot initiation,
anticoagulants directed against these entities were tested for ability to limit plasma clotting or FX activation capacity of BALF or
culture media. Addition of
tifacogin, a TF pathway inhibitor, effectively blocked either activity, demonstrating that the procoagulant actions of
CEES were TF pathway dependent. Lactadherin, a
protein capable of competing with
clotting factors for
phospholipid-binding sites, was partially effective in limiting these procoagulant actions. These findings indicate that TF pathway inhibition could be an effective strategy to prevent
airway obstruction after SM or
CEES inhalation.