BACKGROUND Patients with cystic fibrosis experience chronic systemic oxidative stress. This is coupled with chronic inflammation of the lung involving bronchial polymorphonuclear neutrophil accumulation and activation. We hypothesised that, during periods of acute respiratory exacerbation, free radical activity and consequent damage would be most marked and that intensive treatment of the infection would result in improvement towards values found during stable periods.

RESULTS During respiratory exacerbations FEV₁ and forced vital capacity (FVC) were lower than in controls (mean differences –2.82 (95% CI –2.12 to –3.52) and –3.79 (–3.03 to –4.55) l, respectively) but improved following treatment (mean change 0.29 (95% CI 0.18 to 0.40) and 0.33 (0.23 to 0.43) l, respectively). Inflammatory markers during exacerbations were significantly higher in patients than in controls with the following mean (95% CI) differences: C reactive protein (CRP), 46 (17 to 75) g/l; neutrophil elastase α₁-antiprotease complexes (NEAPC), 4.4 (1.77 to 7.07) mg/l; white cell count (WCC), 5.3 (4.7 to 5.9) × 10⁹/l. These markers decreased significantly following treatment with the following mean (95% CI) changes: CRP –26 (–10 to –42) g/l; NEAPC –3.1 (–1.3 to –4.9) mg/l; WCC –1.5 (–1.3 to –1.7) × 10⁹/l. Malondialdehyde (MDA) as a marker of free radical activity was significantly higher in patients during exacerbations than in controls with a mean (95% CI) difference of 193 (107 to 279) which improved with treatment (mean change –56 (95% CI –28 to –84) nmol/mmol cholesterol). Red blood cell polyunsaturated fatty acids were significantly lower in patients than in controls with a mean difference of –4.4(95% CI –2.6 to –6.2) moles percent, but did not improve significantly after treatment. Protein carbonyls during exacerbations were not different from controls but did increase with treatment compared with levels during the exacerbation (mean change 0.39 (95% CI 0.11 to 0.67) μmol/g protein). Aqueous and lipid phase scavengers in patients during exacerbations were significantly lower than in controls with the following mean (95% CI) differences: ascorbate, –19.0 (–2.7 to –35.3) μmol/l; sulphydryls, –122 (–77 to –167) μmol/l; retinol, –237 (–47 to –427) nmol/mmol cholesterol; β-carotene, –52.8 (–11.8 to –93.8) nmol/mmol cholesterol; luteine, –50.4 (–10.4 to –90.4) nmol/mmol cholesterol; lycopene, –90.1 (–30.1 to –150.1) nmol/mmol cholesterol. Treatment resulted in improvement with the following mean (95% CI) changes: sulphydryls, 50 (32 to 68) μmol/l; retinol, 152 (47 to 257) nmol/mmol cholesterol; α- and β-carotene, 0.6 (0.0 to 1.2) and 7.6 (0.0 to 15.2) nmol/mmol cholesterol, respectively; α-tocopherol, 839 (283 to 1405) nmol/mmol cholesterol; and lycopene, 8.2 (0.0 to 16.2) nmol/mmol cholesterol.

CONCLUSIONS Abnormalities of markers of inflammation, free radical activity, and radical scavengers were significantly more extreme during acute respiratory exacerbations and showed improvement with treatment. The need to provide protection from inflammation and free radical damage should therefore be dynamic and related to the inflammatory and oxidative processes.