Alterations of pulmonary Surfactant Protein A (SP-A) in bronchoalveolar lavage of human lung transplant recipients
Purpose: SP-A contributes to pulmonary immunologic responses against a variety of lung injuries by both pro- and anti- inflammatory mechanisms. The concentration of SP-A in bronchoalveolar lavage (BAL) has been shown to be decreased in patients with bacterial pneumonia and ARDS, but to our knowledge has not been reported in diseases of human lung transplant recipients. In this pilot study, we hypothesized that the concentration of SP-A in the BAL of lung transplant recipients would vary in patients with allograft rejection or infection, compared to those without allograft disease. Methods: Aliquots of BAL from nineteen lung transplant patients undergoing bronchoscopy were prospectively obtained, and the concentration of total protein in the BAL of each patient was determined. Equal microgram amounts of total protein from each sample were resolved by electrophoresis, and SP-A was visualized by western blot. Transbronchial biopsies and the remaining BAL were processed for microbiologic and pathologic studies to determine the presence or absence of acute rejection, bacterial infection, and viral infection. Results: Of the nineteen patients studied, four had no evidence of allograft disease, three had acute rejection, four had bacterial infections, and eight had viral infections. No patient had more than one diagnosis. The [protein] in the BAL of patients with acute rejection was significantly higher than in those without evidence of graft disease (480 ± 20 vs. 139 ± 17 μg protein/mL BAL, p < 0.001). Two of the three patients with acute rejection had markedly reduced [SP-A], and the other had modestly reduced [SP-A], compared to those with normal allograft function. One of the four patients with bacterial infection, and one of eight with viral infections, had decreased [SP-A]. Conclusions: These results demonstrate decreased concentration of SP-A in the BAL of this series of lung transplant recipients at the time of acute rejection compared to patients with normal allograft function. Additionally, the concentration of total protein in the BAL of patients with acute rejection was significantly greater than in those without rejection. Clinical Implications: We speculate that acute rejection is associated with a decrease in the relative concentration of SP-A in BAL. Validation of this finding and investigation of the mechanism(s) of these observations are warranted as decreases in SP-A concentration may have significant effects on the transplanted lung in terms of both surfactant function and the magnitude of allograft inflammation in acute rejection.
Mariencheck, WI; Tapson, VF; Palmer, SM
Volume / Issue
International Standard Serial Number (ISSN)