Objective To observe the expression levels of serum T lymphocyte subsets and cytokines in patients with different inflammatory phenotypes of bronchial asthma.

Methods A total of 100 patients with acute attack of bronchial asthma were selected as research objects, and they were divided into eosinophil type group (n=51), neutrophil type group (n=31), mixed granulocyte type group (n=11) and oligogranulocyte type group (n=7) according to proportion of inflammatory cells in induced sputum. The levels of interleukin-4 (IL-4), interleukin-17 (IL-17), transforming growth factor β₁ (TGF-β₁) and interferon γ (INF-γ) were detected by enzyme-linked immunosorbent assay; the number of INF-γ⁺CD4⁺T helper cell 1 (Th1) and IL-4⁺CD4⁺T helper cell 2 (Th2) cells was detected by flow cytometry; the Logistic regression model was used to analyze the risk factors of asthma in patients with eosinophil type and neutrophil type.

Results There were significant differences in allergic history, smoking history and disease severity among the groups (P < 0.05). The ratio of Th1 to Th2 (Th1/Th2), INF-γ level and IL-17 level in the eosinophil type group and oligogranulocyte type group were significantly lower than those in the neutrophil type group and mixed granulocyte type group, while the levels of TGF-β₁ and IL-4 were significantly higher than those in the neutrophil type group and mixed granulocyte type group (P < 0.05). Percentage of eosinophils was significantly positively correlated with allergic history, IL-4, INF-γ and TGF-β₁ in patients (P < 0.05), but was significantly negatively correlated with disease severity, Th1/Th2 and IL-17(P < 0.05); percentage of neutrophils was significantly positively correlated with disease severity, smoking history, Th1/Th2 and IL-17 in patients (P < 0.05), but was significantly negatively correlated with IL-4, INF-γ and TGF-β₁ (P < 0.05). Multivariate Logistic regression analysis showed that allergic history, decreased Th1/Th2, increased IL-4, increased INF-γ, increased TGF-β₁ and decreased IL-17 were the risk factors for eosinophilic asthma (P < 0.05 or P < 0.01); smoking history, increased Th1/Th2, decreased IL-4, decreased INF-γ, decreased TGF-β₁ and increased IL-17 were the risk factors for neutrophilic asthma (P < 0.05 or P < 0.01).

Conclusion In patients with bronchial asthma, the different inflammatory phenotypes of asthma are closely related to Th1/Th2 in circulating blood, cytokines and clinical characteristics.