Interleukin-2 levels in exhaled breath condensates, asthma severity, and asthma control in nonallergic asthma

There was evidence that interleukin (IL)-2 and IL-10 in the airways play roles in regulating the asthmatic inflammatory response. The purpose of this study was to measure the levels of these cytokines in exhaled breath condensates (EBCs) from asthmatic airways and their correlation with a clinical assessment of asthma severity. The levels of IL-2 and IL-10 in EBC, Asthma Control Test (ACT) score, and the forced expiratory volume in 1 second (FEV₁) were studied in 28 steroid-free asthmatic patients and 10 healthy volunteers. The results were analyzed according to their allergic status, asthma severity, and body weight. The correlations between IL-2 and IL-10 levels, percent predicted FEV₁, ACT score, and body mass index were also determined. Both IL-2 and IL-10 levels in EBC significantly increased in asthmatic patients, especially in patients with moderate-to-severe persistent asthma, compared with those in normal controls. However, the signification correlations between IL-2 levels and ACT (r = -0.684; p = 0.007), as well as with percent predicted FEV₁ (r = -0.671; p = 0.009), were established only in patients with nonallergic asthma. The elevation of IL-2 levels in EBC in obese subjects was observed but was probably related to asthma severity. The levels of IL-2 and IL-10 in EBC increase in asthmatic patients but only IL-2 levels significantly correlate with the ACT score and percent predicted FEV₁ in nonallergic asthma. Additional studies should be explored to confirm the reliability of ACT score as a predictor of inflammatory response in asthmatic airways.