Abstract: Objective: To investigate the role of anaphylatoxin C5a in patients with asthma.  Methods: A prospective study was performed between September 2006 and February 2007. A total of 33 patients with acute exacerbation of asthma and 13 healthy subjects were recruited into the study. The patients with acute exacerbation of asthma were also studied when they returned to the remission state. Levels of lung function, levels of C5a in induced sputum and cell differential count in induced sputum were determined. Results: The level of C5a in induced sputum was significantly higher in patients with acute exacerbation of asthma ［0.85(0.68-2.13) μg/L］ than that in patients with stable asthma ［0.45(0.26-0.88) μg/L, Z=-2.193, P=0.013］; Sputum C5a levels in stable asthma patients were significantly higher than those in healthy controls ［0.14(0.06-0.45) μg/L, Z=-2.141, P=0.015］. The level of C5a in patients with severe exacerbation ［2.21(1.27-9.0) μg/L］ was significantly higher than those in patients with mild exacerbation ［0.34(0.17-0.63) μg/L］ and moderate exacerbation ［0.85(0.55-1.67) μg/L, χ²=12.330, P=0.001］. The level of C5a in induced sputum was positively correlated with the number of total cells count (r=0.797, P=0.004), neutrophils (r=0.504, P=0.032) and macrophages (r=0.424, P=0.036) in acute exacerbation of asthma. Conclusion: C5a levels in induced sputum could be identified as an important prognostic biomarker, which involved in asthma’s pathogenesis.

Key words: Anaphylatoxins, Asthma, Bronchi, Sputum