Histologic prognostic indicators for the lung allografts of heart-lung transplants.

The histologic changes in transbronchial lung biopsy specimens of heart-lung transplant patients were graded during episodes of acute rejection and when patients were well. Infection was strictly excluded from all episodes studied. Grade of severity of rejection was determined by the magnitude and extent of the inflammatory infiltrate. Biopsy specimens, obtained 1 year after the initial biopsies, were examined for histologic evidence of airway submucosal fibrosis, and each patient's clinical status at this time was recorded. The biopsy material from 22 long-term survivors was studied. On 16 occasions the specimens showed no evidence of rejection (grade 0). Twelve of these sets of specimens were from clinically well patients, and four were from the patients who had clinical evidence of rejection. The other six sets of specimens, from clinically well patients, showed evidence of rejection: three grade 1 and three grade 2. One year later, the clinically well patients had normal biopsy histology without fibrosis and normal lung function. Bronchiolitis obliterans had not developed in any patient. There were 27 episodes of rejection in the 22 patients, of which 23 were confirmed histologically. Eleven sets of specimens had grade 1 acute rejection, eight grade 2, and four grade 3. Three of these patients died, and bronchiolitis obliterans was confirmed at necropsy. Lung fibrosis was more common in specimens taken after 1 year, and lung function was depressed in these patients. The histologic grading of transbronchial lung biopsy material, although still in the early stages of development, provides some predictive value to the long-term outcome of the lung transplant patient, in development of both bronchiolitis obliterans and lesser fibrotic changes.