We enrolled 10 CF patients who consecutively had been admitted at the CF Center of the Hospital of Cerignola "G. Tatarella" for parenteral (i.v.) antibiotic therapy during acute respiratory exacerbation, and 11 stable CF patients. Exacerbation was defined as a deterioration in symptoms perceived by the patient and included an increase in cough, sputum production, dyspnoea, decline in forced expiratory volume in 1 sec (FEV 1 ) compared with previous best, weight loss and fever [27] . Each patient was given a clinical score obtained from the sum of the individual parameters (0 = no symptom; 1 = moderate; 2 = severe). Serum C-reactive protein (CRP) was assessed as a marker of active inflammation [28] . CF patients were compared with 7 primary ciliary dyskinesia (PCD) patients.