18 Effect of cystic fibrosis (CF) serum on the kinetics of phagocytosis of pulmonary alveolar macrophages (PAM)

Abstract

Although several organs are clearly affected in CF, lung disease constitutes the principal factor which determines patient prognosis. In the present work, a kinetic assay using CF-PAMs was designed in order to investigate the effect of CF serum on the phagocytic function of these cells. The phagocytic process was treated as an enzymatic system, with the principal interest being the determination of the Michaelis constant and the maximum velocity, by means of the Eisenthal and Cornish-Bowden direct plot. Bronchopulmonary lavages were performed on 8 CF children, 8 children with non-CF infectious lung disease, and 5 normal children who were diagnosed as having a foreign body in the air passages, without infection; all the controls were age and sex matched to CF patients. The CF serum had no effect on the kinetic of phagocytosis of Candida albicans by CF- and control PAMs. An interesting finding was the decrease in the affinity of CF-PAMs for the Candida yeasts, which was suggested by an increased value of the corresponding Michaelis constant; simultaneously, the CF-PAMs appeared to be less effective than the ones coming from the infected non-CF, or the non-infected human respiratory tracts. In conclusion, the phagocytic capacity of human PAMs might not be affected by CF serum; a cell failure due to the interaction between CF-PAMs and an altered lung milieu is proposed.