Increased IL-17A secreting CD4+ T cells, serum IL-17 levels and exhaled nitric oxide are correlated with childhood asthma severity

Summary Background Measuring fractional exhaled nitric oxide (FeNO) is a simple and non‐invasive method for assessing airway inflammation. IL‐17 plays an important role in T cell‐dependent inflammatory response that occurs in allergic asthma, it could act as a potent activator of inducible nitric oxide synthase (iNOS) to amplify FeNO levels. Objectives To evaluate the differences in the CD4+IL‐17A+ T cell counts, serum IL‐17 levels, and FeNO levels in children with mild intermittent to moderate to severe persistent asthma classified by using the Global Initiative for Asthma (GINA). Methods One hundred and twenty asthmatic children divided into the mild intermittent (n = 42), mild persistent (n = 42), and moderate to severe persistent (n = 36) groups, and 20 healthy controls were recruited for the study. Information obtained at visits included the assessment of asthma severity according to GINA guidelines and C‐ACT, lung function parameters, FeNO levels, CD4+IL‐17A+ T cells counts from PBMCs, iNOS production by sputum cells and serum IL‐17 levels. Results Serum IL‐17 and FeNO levels were significantly higher in mild to severe persistent asthmatic patients than in intermittent asthmatics or healthy controls (P