Platelet-specific alpha-granule proteins and thrombospondin in bronchoalveolar lavage in the adult respiratory distress syndrome

Levels of platelet-specific alpha-granule proteins, PF, BTG, and TSP were measured in BAL fluids of patients with the ARDS, ILD, and normal healthy subjects, comprising two separate cohorts. In both groups BAL showed elevated levels of BTG and thrombospondin in ARDS patients. Low levels of PF4 were found in BAL and did not differ between ARDS and control patients. The BTG:PF4 ratio was 2:1 or greater in BAL of ARDS patients and of control subjects with other lung diseases, suggesting in vivo release. In ARDS patients, the ratio of TSP to BTG exceeded that usually found in plasma. In ARDS patients in group 2, BAL levels of TSP, BTG, and total protein correlated strongly with the composite injury scores that were used to quantitate their degree of lung injury. Elevated levels of platelet-derived proteins, which modulate chemotaxis of inflammatory cells and promote connective tissue reorganization, occur in the alveolar compartment of ARDS and ILD patients but are usually undetectable in BAL of healthy control subjects. Levels in these patients in BAL fluid are nonspecific indices of the severity of lung injury in patients with ARDS.