Phagocytosis of Candida albicans by alveolar macrophages from patients with cystic fibrosis

Abstract

Cystic fibrosis (CF) children suffer from chronic and progressive lung disease characterized in most cases by persistent Pseudomonas aeruginosa colonization. In the present work, a kinetic assay using CF alveolar macrophages (CF-AM) and polymorphonuclear leukocytes (PMN) was designed in order to investigate the effect of CF serum on the phagocytic function of these cells. Bronchopulmonary lavages were performed on eight CF children, eight non-CF children with infectious lung disease, and five normal children who were diagnosed as having a foreign body in the air passages, without infection. Serum samples were taken from eight CF and eight normal children; all the controls were age and sex matched with CF patients. The CF serum had no effect on the kinetics of phagocytosis of Candida albicans by CF and control AM and PMN. A suggestive finding was the decrease in the Michaelis-Menten constant ( K m ) for the interaction of CF-AM with Candida, measured as the abscissa to the origin of a Lineweaver-Burk plot. The Michaelis-Menten constant obtained from the challenge of AM with yeasts in a medium containing normal fresh serum was 9.28 for the noninfected controls, 2.86 for the infected controls, and 21.38 for the CF patients; the last was significantly different from both controls ( P < 0.01).