ABSTRACT
Association of asthma with Type 2 T- helper system is well realized. Recent clinical evidence show that acute, severe exacerbations of asthma are associated with recruitment and activation of neutrophils in the airways. The lymphocytes T helper 17 [Th17] cells can probably recruit neutrophils to an inflammatory site through producing IL-17. The objective of this study was to investigate the level of interlukin-17 [IL-17] in serum and sputum of asthmatic subjects. Also, the study aimed at evaluating the correlation between concentrations of IL-17 and the frequency of inflammatory cells in the sputum of asthma at different stages. Fifty newly diagnosed asthmatics and 12 non-asthmatics healthy subjects, as the control group, entered this prospective study. None of them reported any recent history of infection and steroid usage. Then, samples from venous blood and sputum [Induced by Hypertonic saline%5] were obtained. The severity of asthma was classified according to GINA 2004 guidelines. The Concentrations of IL-17 in serum and supernatant of induced sputum were determined by ELISA method. Total serum IgE level was also determined in order to classify asthmatic subjects into allergic and non-allergic groups. As the findings of the study suggest, serum IL-17 level was significantly higher in asthmatic patients than in the normal control subjects [78.8 +/- 58.7 vs 17.7 +/- 2.4 pg/dl, P=0.025]. IL-17 was found to be significantly increased in sputum of the subjects with asthma, as compared to the control subjects [31.6=/-20.9 vs 21.5 +/- 16.6 pg/dl, P=0.012]. In addition, allergic and non-allergic asthmatic patients showed a significantly higher concentration level of serum IL-17 than the normal controls [80.8 +/- 50.3, P+0.023 and 102.7 +/- 43.6, P=0.002vs 17.7 +/- 2.4 ng/ml]. But, it was found that the levels of both serum and sputum IL-17 in the allergic asthma group were not significantly higher than those in the non-allergic asthmatics. Moreover, serum IgE level was significantly higher in allergic asthmatic patients than non-allergic asthmatic and normal control subjects [295.8=/-168 vs. 99.1 +/- 90.0 P=0.001 and 49.7 +/- 41.8, P=0.001]. The results further revealed that macrophage was decreased in sputum but neutrophil and eosinophil were significantly increased. However, the increase of IL-17 was not correlated with asthma severity. Besides, there was no significant difference between allergic and non-allergic asthmatic subjects, in terms of IL-17. We propose that IL-17 may play a role in the airway inflammation of asthmatics by recruiting neutrophils into the lung, no matter if they are suffering from allergic or non-allergic asthma