ULTRASTRUCTURAL PATHOLOGY OF THE ALVEOLAR TYPE-II PNEUMOCYTES OF HUMAN DONOR LUNGS - ELECTRON-MICROSCOPY, STEREOLOGY, AND MICROANALYSIS

Alveolar type II pneumocytes (PII) were studied in 12 human donor lung s perfused with modified Euro-Collins solution during single-lung tran splantation (SLTx). While one lung was transplanted, the contralateral donor lung (cDL) was fixed at the time of SLTx for examination by ele ctron microscopy, stereology, and microanalysis. Three groups were the n formed: group A (n = 7), cDL without contusions, uneventful early po stoperative course; group B (n = 3), cDL with contusions, uneventful e arly postoperative course; group C (n = 2), cDL without contusions, ea rly postoperative respiratory dysfunction. The major findings were tha t the presence of contusions had no effect on PII ultrastructure and t hat intracellular surfactant-storing lamellar bodies of cDL in group C were characterized by a higher volume-to-surface ratio (VsR) and larg er area per cell profile than group A. Correlation analysis based on p ooled data (groups A and C) showed that ischaemic time had little effe ct on PII ultrastructure and bore no relationship to postoperative cli nical variables. The duration of preoperative donor intubation had a p ronounced influence on ultrastructure and postoperative clinical varia bles. The stereologically estimated amount of intracellular surfactant and mitochondrial VsR were the only ultrastructural parameters that w ere significantly associated with early postoperative oxygenation. Lam ellar bodies were the only ultrastructural components found to have a significant relationship to postoperative intubation time. The ultrast ructural integrity of type II pneumocytes of human donor lungs is an i mportant determinant of early respiratory function following clinical lung transplantation.