Adult respiratory distress syndrome after allogeneic bone-marrow transplantation: evidence for a neutrophil-independent mechanism.

5 patients in whom the adult respiratory distress syndrome (ARDS) developed after bone-marrow transplantation (BMT) for chronic myeloid leukaemia are described. Donors in all cases were siblings who were matched for all major-histocompatibility-complex determinants. All patients were neutropenic to varying degrees at the onset of respiratory symptoms. Histological evaluation in all patients at necropsy showed diffuse alveolar damage with no evidence of intrapulmonary neutrophil sequestration. No patient had detectable levels of plasma peroxidation products, which were measured as an index of neutrophil oxidant function. Significantly increased clearance of inhaled 99mTc-diethylene-triamine-pentacetate was a uniform finding, suggesting impaired alveolar-capillary barrier function in keeping with ARDS. An increase in an index of lung epithelial permeability leading to ARDS may develop in neutropenic patients who have evidence of neither intrapulmonary neutrophil sequestration not tissue oxidant injury. ARDS after BMT is probably multifactorial in aetiology, but neutrophil-derived oxidant products play no part in its genesis.