New meta-study suggests BAL can be an important tool for studying chronic lung rejection

February 18, 2013 – The DCRI’s Scott Palmer, MD, and others analyzed 100 medical journal articles to better understand the association between BAL parameters and bronchiolitis obliterans syndrome.

Bronchoalveolar lavage (BAL) is a vital tool for understanding bronchiolitis obliterans syndrome (BOS), DCRI researchers concluded in a recent meta-analysis.

The study, by Scott Palmer, MD, and Jamie Todd, MD, of the DCRI and V.E. Kennedy of the Division of Pulmonary, Allergy, and Critical Care Medicine at Duke University Medical Center, appears in the online version of the American Journal of Transplantation.

BOS, sometimes called chronic lung rejection, is a significant limiting factor for long-term survival after lung transplantation. A patient is typically diagnosed with BOS when his or her lung function decreases substantially and does not improve. Almost half of all lung transplant recipients will develop BOS within 5 years after transplantation. Despite the severity and prevalence of the syndrome, the mechanisms of BOS are not well understood.

BAL is a diagnostic tool that lung transplant recipients undergo as part of their clinical care. It involves obtaining a sample of fluid from the lungs by inserting a flexible tube through the windpipe. This allows clinicians to study the cellular composition, cytokine profile, and protein constituents of the fluid. Researchers have conducted numerous studies of the BAL fluid of BOS patients, but there was no available summary of this body of research.

To establish the strength of the association between specific BAL parameters and BOS, the Duke researchers searched PubMed for all articles containing the terms “lung transplant” and “bronchoalveolar lavage” published between 1991 and 2012. After excluding non-relevant entries, the researchers found 100 articles. These articles were categorized with respect to study design, number of patients included, follow-up time, and BAL parameters assessed. Of these parameters, neutrophil count (a measure of a type of white blood cells), interleukin-8 (a chemokine), alpha defensins (a family of peptides), and the matrix metallopeptidase-9 (MMP-9) enzyme appeared to be most strongly associated with BOS.

The researchers concluded that there are more opportunities to better understand BOS through the analysis of BAL. These opportunities can be leveraged, they said, by use of increased sample sizes, covariant adjustment, and standardization of the BAL technique. Such developments could lead to further insights into the pathogenesis of a complex disease.