CXCL8 and cystic fibrosis: Findings from small single-center studies are limited, but support an association between sputum biomarkers and disease status in CF, as determined by pulmonary function tests, chest radiograph scores, HRQoL measures, and illness severity scores (e.g., Shwachman–Kulczycki score).97 Significant correlations between FEV1 and sputum inflammatory measures, including neutrophil counts, interleukin (IL)-8, and neutrophil elastase, have also been demonstrated in a diverse CF population across multiple centers participating in four CF clinical trials.99