REVISITED PHYSICOCHEMICAL AND TRANSPORT-PROPERTIES OF RESPIRATORY MUCUS IN GENOTYPED CYSTIC-FIBROSIS PATIENTS

We investigated the physicochemical and transport properties of sputum samples collected in physiotherapy from a well-documented group of 27 cystic fibrosis (CF) patients with identified CF genotypes. Sputum sa mples were characterized ex vivo for their water content, surface prop erties (surface tension and contact angle), rheologic properties (visc osity and elastic modulus), and transport properties (mucociliary and cough transport). These data were analyzed in relation to the clinical status of the patients (FEV1, FVC, Shwachman score, Brasfield score, nutritional status), their genotype, and the degree of infection of th eir sputa (leukocyte and Pseudomonas aeruginosa counts), We observed n egative and significant correlations between mucociliary transport and elastic modulus of the patients' sputum (r = -0.63, p < 0.01), and be tween the cough transport and contact angle of the sputum (r = -0.81, p < 0.8001), respectively. The P. aeruginosa count was also significan tly correlated with the sputum water content (r = -0.53, p < 0.02) as well as with the cough transport of the sputum (r = -0.65 p < 0.01). I n CF patients with a sputum leukocyte count > 2,000/mm(3), the sputum water content (p < 0.02), FEV1 (p < 0.05) and FVC (p < 0.02) were sign ificantly lower than those of CF patients with a leukocyte count less than or equal to 2,000/mm(3), CF patients with a homozygous Delta F 50 8 genotype had significantly greater values of sputum water content (p < 0.05), and cough-transport capacity (p < 0.05) than did heterozygou s patients. No correlation was observed between the sputum properties and any of the clinical data. These results suggest that the control a infection should be emphasized in CF, since it can directly or indire ctly modulate the degree of hydration, and therefore the physicochemic al and transport properties, of airway secretions.