| Objective:To explored the role of Tfh cells in Tuberculosis immunity by detecting the proportion of Tfh cells in peripheral blood and related cytokines and transcription factors of children and adolescents with pulmonary tuberculosis,latent tuberculosis infection and healthy controls,which provided basis for the diagnosis and treatment of tuberculosis in children and adolescents.Methods:The study using a case-control study design.The patients with active tuberculosis aged 18 and under who were treated at designated tuberculosis hospitals in Urumqi from July 2017 to March 2019 were selected as case groups,and latent infection groups and healthy controls that met the criteria were selected during the same period,with 25 cases in each group.Collect demographic data and blood samples of the included subjects.Flow cytometry was used to compare the proportion of CD4+CXCR5+Tfh cells and CD4~+CXCR5~+ICOS~+Tfh cells in the peripheral blood of the three groups.Differential protein expression levels of cytokines IL-4,IL-17A,IL-21,TNF-?,and IFN-?in the plasma of the three groups were analyzed by flow cytometric multiplex protein quantitative technology.The mRNA levels of Tfh cell-related transcription factors Bcl-6,IL-21 and CXCL13 were detected by real-time quantitative PCR.Results:(1)In the tuberculosis group,there were 10 male patients,8 han patients and 10 uygur patients,aged 7-18 years,with an average age of(15.88±2.403)years.There were 14 male students,10 han and 12 uygur in the latent infection group,aged from 11 to 18 years,with an average age of(15.72±1.815)years.In the healthy control group,there were 13 male students,8 han students and 13 uygur students,aged from 9 to18 years old,with an average age of(15.00±2.398)years old.There were no statistically significant differences among the three groups in age,gender and ethnic groups(P>0.05).(2)The proportion of CD4~+CXCR5~+Tfh cells was significantly different between the three groups(P<0.05).The pulmonary tuberculosis and latent infection had a lower percentage of peripheral blood than healthy controls.(3)Plasma cytokines IFN-?and TNF-?increased significantly in patients with pulmonary tuberculosis,and the difference was statistically significant(P<0.05).The cytokines IL-21 was no significant difference in three groups,but there was a decreasing trend in the latent infection and the tuberculosis patients.(4)The level of transcription factor IL-21 mRNA was significantly increased in patients with tuberculosis,and the difference was statistically significant(P<0.05).(5)The level of cytokine IL-21 was positively correlated with the proportion of peripheral Tfh cells(r=0.259,P=0.025).Conclusion:(1)CD4~+CXCR5~+Tfh cells in peripheral blood play their role in children and adolescent tuberculosis immunity through the mechanism of metastasis from peripheral blood to lung parenchyma or mediastinal lymph nodes.(2)IL-21 mRNA levels of pulmonary tuberculosis are significantly higher than those of latent tuberculosis infection and healthy control,suggesting that IL-21 may be involved in the immune response mechanism of tuberculosis.(3)The decrease of peripheral blood Tfh cell frequency in children and adolescents with tuberculosis and latent infection is related to the decrease of plasma cytokine IL-21. |
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