Sputum through its inflammatory cell, bacterial, volatiles, mucin and protein content represent an important tool for the diagnosis and monitoring of CF and other respiratory diseases, beside for the study of disease pathogenesis and its treatment. Measurement of these components is largely sophisticated and quantifiable, and the search for novel biomarkers of CF airways disease in this biofluid is under way [16, 47] . The finding of MPs in sputum raises some intriguing questions on the pathophysiological role of MPs in pulmonary epithelium. Our data strongly support the notion that MPs are derived from granulocytes of CF patients, and this correlates with massive influx of neutrophils into CF airways and their accumulation on the surface of the airway epithelium [34] . In this environment, neutrophil-derived MPs could contribute to selfperpetuating inflammatory cycle, and may account for the exaggerated proinflammatory response of cells in CF patients.