Analysis of clinical features of adult asthma according to blood basophil and their association with cytokines in exhaled breath condensate

Purpose: Although basophils are major effector cells involved in asthma, their pathophysiological role in asthma remains uncertain. In this study, we investigated the relationship between blood basophils, clinical features in asthmatics, and cytokines in exhaled breath condensate (EBC) which could be noninvasively obtained. Methods: A total of 13 adult asthmatics were prospectively enrolled. We obtained information on demographics, asthma control levels, history of acute exacerbation as well as the asthma control test and Quality of Life Questionnaire for Adult Korean Asthmatics (QLQAKA) scores. Peripheral blood and EBC samples were collected, and pulmonary function test was also performed. The association between blood basophil count and clinical feature and severity of asthma or inflammatory cytokines in EBC was analyzed. Results: The percentage of blood basophils was positively correlated with that of blood eosinophils (Spearman r= 0.665, P= 0.013). The number of acute exacerbations was significantly larger (1.2 +/- 0.6 vs. 5.3 +/- 5.8, P= 0.049) in the group with blood basophils >= 50 cells/pL, while the QLQAKA score was lower (68.8 +/- 7.9 vs. 49.0 +/- 12.0, P= 0.028). There were no significant differences in age, atopy status, smoking history, and forced expiratory volume in 1 second according to blood basophil count. Blood basophil count was positively correlated with interleukin-33 (IL-33) (r= 0.651, P= 0.016) and IL-17 (r= 0.732, P= 0.004) in EBC. Conclusion: Blood basophils may be associated with frequent asthma exacerbations and lower quality of life due to asthma. IL-33 and IL-17 may be the key mediators that stimulate basophils to participate in the pathogenesis of asthma.