Inflammatory Mediators in CF Patients

Patients with cystic fibrosis (CF) succumb to airway infection and inflammation, and determining the extent and nature of the infecting agents, as well as the extent and nature of the inflammatory response, is critical to understanding the pathophysiology of the disease and how to intervene (1 ,2 ). However, for many years this aspect of the disease was glossed over, because the “usual” indicators of infection and inflammation (e.g., leukocyte count, acute-phase reactants, cultures, even cytokine levels), measured in the blood, were unimpressive in CF patients, and correlated poorly with clinical status. Even more detailed investigations into the function of circulating cells of host defense, such as neutrophils, lymphocytes, or monocytes, were not revealing. However, evaluation of infection and inflammation at the infected and inflamed site, that is, in the airways, has proven to be considerably more informative. For example, Berger and colleagues determined that circulating neutrophils from patients with CF behaved normally and could be activated by Pseudomonas and ingest and kill the bacteria in the presence of complement, but neutrophils recovered from bronchoalveolar lavage fluid from CF patients often failed to do so (3 ). He went on to show that, because of the high levels of uninhibited elastase in the airways of patients with CF, either the complement receptors or the complement opsonins were cleaved into nonfunctional states (4 ). Therefore, once neutrophils arrive at the site of inflammation in the CF lung, they are altered by that environment, to the detriment of the host defense. Thus, sampling the relevant site by bronchoalveolar lavage (BAL) gives useful information not obtainable in other ways. Although expectorated sputum has been used as a noninvasive way of sampling the airway, BAL is considered to yield the most accurate measure of the inflammatory process in the CF airway (5 ). Therefore, this chapter focuses on the use of BAL in CF research. A number of research groups have utilized BAL to study CF lung disease during the last decade. Included are studies that reveal the large extent of infection and inflammation in the CF airway, even in the earliest stages of the disease (6 -12 ), as well as serial lavage studies (sampling the airways of the same patient over time) before and after an anti-infective or anti-inflammatory intervention (13 -15 ). With many new anti-inflammatory and other treatments being proposed for CF lung disease, it is imperative to have a safe and standardized way of sampling the milieu in the lower airways. More recently, the central role of the epithelium in orchestrating the inflammatory response has also become clear, and sampling of epithelial cells in the airway has also become useful in describing the inflammatory state of the patient (16 -18 ). Our center has devised a standardized method of bronchoalveolar lavage (and subsequent processing of the fluid obtained) and epithelial brushing that has provided useful information both for research and for clinical purposes (3 ,4 ,6 ,16 ,17 ,18 -24 ). It is particularly important to process and store the fluid in such a way that many different measures can be obtained simultaneously, or so that the fluid can be used at a later time for additional determinations, since the patient has been subjected to an invasive procedure and the maximum information should be extracted from it. When patients are in periods of clinical stability, the procedures described herein give reproducible findings from week to week or month to month. When patients have been treated or have become ill in the interval, values move in the expected directions.