The characteristics of pleural effusions without clinical evidence of infection or rejection have been studied following single lung transplant in nine patients [18]. The pleural fluid was initially bloody, exudative, and neutrophil-predominant (figure 1). Over the next seven days, the percentage of neutrophils and the lactate dehydrogenase (LDH) concentration decreased, while the percentage of macrophages and lymphocytes rose. Resolution of daily pleural fluid output generally paralleled a decrease in pulmonary edema.