Features Of T Cell Subsets And Establishment Of Flow Cytometry-based DiagnositicMethod For Childhood Tuberculosis

Childhood tuberculosis, it is fairly to say that in the past too little attention has been paid to the diagnosis and treatment in young children. Recently, much attention has been paid to this disease, however, there is limited information concerning the immune status of childhood tuberculosis. In this project, we have systematically studied the T cell subsets by using multicolor Flow Cytometry. Interestingly, we find that for the groups older than 5 years, the number of total T cells, αβT, vδ2+γδT, mucosal-associated invariant T cells (MAIT), CD4+ helper T cells (Th), CD8+T cells, CD4/CD8 double negative T cells (DNT) and CD4/CD8 double positive T cells (DPT) were significantly lower in the patient group than healthy controls. In addition, the percentages of central memory T cells (TCM) from Th, CD8+T and regulatory T cells (Treg) were significantly lower in the patient group older than 5 years. For the groups younger than 5 years, only the numbers of vδ2+γδT and DNT and the percentage of TCM of Tregs were significantly lower in the patient group than healthy control group, while the percentage of TEM of Tregs was significantly higher in the patient group. There were no significant differences between other groups. These results indicate that T cell subsets have been extensively modified in childhood tuberculosis (TB), particularly in the patients older than 5 years, which forms a strong basis for the future studies.Accurate diagnosis of childhood tuberculosis is always a major challenge for the time being. To this goal, we have developed a multi-parametric flow cytometry-based diagnostic work up (FC assay) for childhood TB. If the percentage of Mycobacterium Tuberculosis (Mtb) antigen-specific TNF-α+IFN-γ+o r IL2+IFN-γ+T cells exceeds 0.005%, we consider that the object as TB patient. We compared FC assay with T-SPOT.TB, and found that the sensitivity of FC assay was 78.6%, which is higher than T-SPOT. TB (71.4%) in the children with confirmed TB. The specificities of both assays were 100%. The sensitivity of T-SPOT.TB in the patient group younger than 5 years was higher than the patient group older than 5 years. The sensitivity of FC assay is not influenced by the age. One interesting finding is that in patients with pulmonary tuberculosis (PTB) or PTB combined with extra-pulmonary tuberculosis (EPTB), the sensitivities of FC assay were 100%. However, the sensitivities of T-SPOT.TB were 81.8% and 88.9% respectively. From these results we can conclude that FC assay is a promising diagnostic approach for childhood TB, particularly for patients with PTB or PTB+EPTB.