Materials and Methods:Hypertonic saline induced sputum was obtained from asthma in stable state (n=88) and in exacerbation (n=55). Differential cell count was done. IL-8 was measured using sandwich ELISA. The levels were analyzed in terms of airway obstruction (FEV1) and inflammation (neutrophil and eosinophil % of the airway) and exacerbation frequency and lung functions over 1 year or longer follow up.
Results: IL-8 levels were significantly correlated with the percentages of neutrophils (r=207, p=0.012) and neutrophils count (r=0.277, p=0.001) in sputum, and inversely with the levels of FEV1% (r=-0.277, p=0.028) in total asthmatics. The correlations of IL-8 levels with percentages of neutrophils (r=0.312, p=0.003) and FEV1% (r=-0.252, p=0.018) were also observed in stable asthmatics. In the exacerbation group, IL-8 levels were inversely correlated with FEV1% predicted values (r=-0.272, p=0.045). In long term follow up over more than 1 year, IL-8levels were positively correlated with annual number of exacerbation (n=109, r=0.227, p=0.017).
Conclusion: sputum IL-8 is related with neutrophilc inflammation rather than eosinophilc inflammation of asthma. In long - term follow up of asthma, increase of sputum IL-8 may be one of susceptible factors for frequenct exacerbation.