Priming of neutrophils for enhanced oxidative burst by sputum from cystic fibrosis patients with Pseudomonas aeruginosa infection.

Neutrophils accumulate in the lungs of cystic fibrosis (CF) patients and inflict tissue damage by release of oxygen radicals and proteases. Here we report on the ability of sputum to prime neutrophils for enhanced release of oxygen radicals. Sol phase was prepared by ultracentrifugation of sputum obtained from CF patients attending the CF Clinic, Rigshospitalet, Copenhagen. The oxidative burst response of neutrophils from healthy individuals was measured by oxygen consumption, superoxide production and chemiluminescence. Neutrophils were preincubated with sputum or buffer and then stimulated with f-Met-Leu-Phe or zymosan. Appropriate controls were included in the experiments. It was shown that neutrophils preincubated with CF sol phase and stimulated with f-Met-Leu-Phe generated a three- to five-fold higher chemiluminescence response than those preincubated with buffer. There was no enhancement of the response when zymosan was used for stimulation of the cells. Neutrophils incubated with sol phase alone exhibited no response. Attempts were made to identify and partially characterize the priming factor(s). It was found that the sputum samples contained bacterial endotoxins. The priming activity was resistant to heating at 100 degrees C for 15 min, and was present only in fractions with molecules larger than 100 KD. It is suggested that the priming factor(s) consist of bacterial endotoxins and/or immune complexes. Activation and enhanced release of oxygen radicals from neutrophils may play an important role in the host defence as well as pathogenesis of tissue damage in the lungs of these patients.