Monocytes in cystic fibrosis: responsiveness to microbial stimuli

Peripheral blood monocytes were obtained from 19 patients with cystic fibrosis (CF) and age-matched paired normal individuals. The oxidative metabolic response of these cells was measured by superoxide anion production before and after stimulation with Salmonella typhimurium or Pseudomonas aeruginosa lipopolysaccharide (LPS). CF monocytes showed slightly greater spontaneous superoxide anion production (14.1 +/- 2.1 SEM nanomoles superoxide anion/10(6) monocytes/180 min; n = 12) than normal monocytes (9.5 +/- 1.4; n = 12), P = 0.009. No differences between CF and normals were found in LPS-stimulated superoxide anion production (CF = 33.5 +/- 4.6, n = 13; normal = 33.8 +/- 4.2, n = 13). Furthermore, CF monocytes responded to both P. aeruginosa and S. typhimurium LPS stimulation as well as to recombinant interferon-gamma. Superoxide anion production of CF monocytes was comparable in autologous serum and in normal serum, and responses of patients colonized with P. aeruginosa and P. cepacia did not differ. We conclude that CF monocytes have a slightly increased metabolic level and, despite chronic infection, are capable of a further response to exogenous microbial stimuli.