Eosinophil activation in the lung is related to lung damage in adult respiratory distress syndrome.

The concentrations of eosinophil cationic protein (ECP), a specific granule constituent of eosinophil granulocytes, were measured in bronchoalveolar lavage (BAL) fluid from patients with adult respiratory distress syndrome (ARDS). The mean level was 163 +/- 85 (SD) micrograms/L and significantly increased (p less than 0.001) compared with the levels in control subjects (19 +/- 18 micrograms/L). The BAL fluid concentrations of myeloperoxidase (MPO) were also significantly increased in ARDS, indicating a local neutrophil activation. A significant correlation was found between BAL fluid ECP and MPO, suggesting a common activator of eosinophils and neutrophils. No relation was seen between BAL fluid ECP or MPO and degree of complement consumption, suggesting that other mechanisms besides complement activation may underlie granulocyte activation in ARDS. Lavage ECP levels correlated strongly with the severity of lung damage defined by pulmonary oxygenation index (PaO2/inspired fraction of O2). Activation of eosinophils, neutrophils, and the complement system is not specific for ARDS but was also observed in patients after major surgery, but at a significantly lower level (p less than 0.001). It is concluded that eosinophil activation is part of the inflammatory process in the lung in ARDS. The association observed between elevated lavage fluid levels of ECP and reduced pulmonary function in ARDS might reflect a pathophysiologic role for ECP and other cytotoxic eosinophil products in this syndrome and should be evaluated.