T Helper 17 Cells and Regulatory T-Cell Imbalance in Paediatric Patients with Asthma

Asthma is a chronic inflammatory disorder of the lung, which is thought to be determined by the balance between the T helper (Th)2 and Th1 responses. This study evaluated whether the balance between Th17 cells and regulatory T cells (T_reg) was impaired in asthma patients. The proportion of peripheral blood Th17 cells of the total CD4⁺ cell population in asthma patients was significantly higher than in controls (mean ± SD 0.72 ± 0.5% versus 0.31 ± 0.4%, respectively). The proportion of peripheral T_reg cells in asthma patients was significantly lower than in controls (mean ± SD 12.1 ± 4.6% versus 27.2 ± 7.5%, respectively). Analysis of mRNA generally confirmed the flow cytometry data, suggesting that the changes in cytokine levels were mediated at the transcription level. In paediatric asthma patients, the CD4⁺ T-cell phenotype was skewed toward the Th17 phenotype, suggesting that a Th17/T_reg functional imbalance plays a role in asthma.