IL-7 potential function in pulmonary TB

The study aims to find some other functions of IL-7 in control TB and screen a new host marker in small groups of TB patients and controls to identify promising markers for large-scale testing. Real-time RT-PCR is used to evaluate the stability of IL-4 and IL-7 mRNA in the presence of Actinomycin D in whole blood from active TB cases and uninfected healthy controls. Flow cytometry and cytokine secretion assays were used to study the IL-7 potential function. The Th2/Th1 (IL-4/IFN-γ) mRNA ratio in unstimulated cells in whole blood was higher in TB subjects than that in controls. The mRNA half-life of Th2 agonist IL-4, but not Th1 agonist-like IL-7, was prolonged in subjects with TB compared to healthy volunteers (~ 5-fold, p =0.001), and the IL-4/IL-7 ratio was higher in TB patients compared to controls (p=0.001). IL-7 can mediate the level of multifunction PPD-specific CD4+ T cells secreting any one of IFN-γ and IL-2 or both of them to increase host protective immunity. The IL-4/IL-7 ratio may be an important biomarker of prognosis in human tuberculosis.