RESUMO
INTRODUCTION AND OBJECTIVES: Th17 lymphocytes are now widely believed to be critical in various chronic pulmonary diseases. However, there is still a small number of investigations regarding children. We aimed to assess the percentage of Th17 lymphocytes and IL-17A in peripheral blood of children with chronic obstructive lung diseases. PATIENTS AND METHODS: We included a total of 42 children: 20 with bronchial asthma (BA), 12 with cystic fibrosis (CF) and 10 healthy children without a history of allergies, aged 4-17 years. Th17 cells (CD3+CD4+CD161+CCR6+) were determined in peripheral blood by flow cytometry. The concentration of serum IL-17A was measured by ELISA. RESULTS: The BA patients had a significantly higher percentage of Th17 (12.40±1.16%) compared to the CF children (7.64±0.87%, p=0.0035) and healthy (7.25±0.45%, p=0.008). Stratifying the BA group, we found higher levels of Th17 in patients with severe BA (p=0.03), whereas patients with moderate BA had Th17 cells close to those in CF and healthy children. We found that patients with better control of BA had Th17 closer to those with CF (p=0.98) than BA children with poor control (p<0.001) (post hoc, Bonferroni correction). CF patients with concomitant P. aeruginosa infection showed slightly higher percentages of Th17 cells than those without infection (8.08±3.09% vs. 6.25±2.42%, p=0.294). CONCLUSIONS: The percentage of Th17 cells was significantly increased in the peripheral blood of children with severe BA compared to the children with moderate BA, which suggests that the former could possibly benefit from future target therapies.