Assessment of Rheological Parameters of Human Sputum.

This study includes two visits to 48 hours apart. During the first visit : * Patients with COPD or cystic fibrosis will have a spontaneous expectoration * Then all study participants will have an induced expectoration with hypertonic salin solution (4.5%). During the second visit : * Patients with COPD or cystic fibrosis will have a spontaneous expectoration * Then, patients with COPD, asthma and healthy volunteers will have an induced expectoration with hypertonic salin solution (4.5%). Patients with cystic fibrosis will have a spontaneous expectoration 1 hour after an RhDNAse nebulization. A control spirometry will be perform before each expectoration and during induced expectoration if necessary. All sputum sample collected will be homogenized and then divided into two equal volumes in order to perform two separate rheological measurements of 15 minutes.