Erythrocytic Glutathione in Cystic Fibrosis
Recent reports have indicated that red blood cell (RBC) antioxidants may function as somatic scavengers in many situations of oxidative stress to the respiratory system comments health and care mall. In these circumstances, the RBC antioxidant activity (traditionally relegated to the reduction of hemoglobin-bound iron) would go well beyond the erythrocytic intracellular content, and would extend to plasma proteins, and other blood cells and surrounding tissues. Examples of this function are the capacity of RBC antioxidants to prevent in vitro vascular leakage and edema of isolated rat lungs exposed to hydrogen peroxide, decrease the injury of ischemic isolated hearts and, when insufflated into the trachea, dramatically improve the survival of rats exposed to 95 percent oxygen. Red blood cell antioxidants are also capable of undergoing adaptive changes upon exposure to an oxidative stress. For example, glutathione (GSH) concentrations are increased in RBCs of healthy smokers and patients with silicosis when compared with age-matched controls. Whether this increase may correlate with the degree of pulmonary dysfunction, and thus provide a clinical marker of functional severity, is not known.
Cystic fibrosis (CF) is a hereditary disorder characterized by progressive airways inflammation and unopposed elastolytic activity leading to early and severe deterioration of respiratory function. The erythrocytic GSH system of these patients has been variably reported as either increased or unchanged. We postulated that such differences might be explained by interindividual variability in the degree of oxidant-antioxidant imbalance suffered by these patients. If so, concentrations of GSH might correlate with the clinical severity of CF. To test this hypothesis, we measured RBC GSH concentrations in a group of adult patients with CF and correlated them with various clinical parameters of severity. Our results support our premise.