Objective: To observe the differentiation of follicular helper T (Tfh) cells in asthma patients during acute exacerbation and post-treatment periods, and explore the clinical significance of Tfh cells in asthma.
Methods: We detected the percentages of CD4⁺CXCR5⁺, CD4⁺ICOS⁺, CD4⁺CXCR5⁺ICOS⁺ T cells in peripheral blood mononuclear cells (PBMCs) by flow cytometry, the level of Bcl-6 mRNA in CD4⁺ T cells by reverse transcription PCR, and the level of interleukin 21 (IL-21) in plasma by ELISA in healthy controls and asthma patients during acute exacerbation and post-treatment release periods. The linear regression analysis was used to analyze the correlations of the level of IL-21 in plasma with forced expiratory volume in one second/forced vital capacity (FEV1/FVC) and forced expiratory volume in one second/prediction (FEV1/Pre) in acute exacerbation period of asthma patients.
Results: The percentages of CD4⁺CXCR5⁺, CD4⁺CXCR5⁺ICOS⁺ T cells in PBMCs, the level of Bcl-6 mRNA in CD4⁺T cells, and the level of IL-21 in plasma increased in acute exacerbation of the asthma patients compared to the healthy controls. After treatment, the percentages of CD4⁺CXCR5⁺, CD4⁺ICOS⁺, CD4⁺CXCR5⁺ICOS⁺ T cells in PBMCs, the level of Bcl-6 mRNA in CD4⁺T cells, and the level of IL-21 in plasma in asthma patients were all reduced as compared with the acute exacerbation period. There were negative correlations between IL-21 and lung function parameters such as FEV1/FVC and FEV1/Pre.
Conclusion: The differentiation of Tfh cells was enhanced in acute exacerbation of asthma patients, and ameliorated after treatment. Tfh cells may participate in the inflammatory reaction of asthma, and the differentiation degree of Tfh cells may reflect the extent of airway limitation in asthma patients.