The pathology of transfusion-related acute lung injury

Transfusion-related acute lung injury is an uncommon condition characterize d by the rapid onset of respiratory distress soon after transfusion. Our un derstanding of its pathophysiology is based on animal models of complement (C5a) and antibody-induced lung injury and a limited number of autopsies. T hese models suggest that transfusion-related acute lung injury is induced b y granulocytes that aggregate in the pulmonary microvasculature after activ ation by transfusion-derived antibodies or biologically active lipids. The published autopsy reports provide little support for this model, as they ar e invariably confounded by underlying pulmonary infection, preexisting dise ase, and resuscitation injury. We report the case of a previously well 58-y ear-old man who died of transfusion-related acute lung injury within 2 hour s of the onset of pulmonary distress; autopsy showed evidence of massive pu lmonary edema with granulocyte aggregation within the pulmonary microvascul ature and extravasation into alveoli. Electron microscopy revealed capillar y endothelial damage with activated granulocytes in contact with the alveol ar basement membranes. These findings provide direct support for the propos ed model of transfusion-related acute king injury pathogenesis.