Abstract: Objective To analyze the changes in proportions of Th cells during Mycobacterium tuberculosis infection. Methods 2 ml heparinized peripheral blood was collected from patients with pulmonary tuberculosis(PTB),extra-PTB(EPTB),lung cancer(LC) and healthy subjects(HS),respectively.T cells secreting IFN-γ,IL-4,IL-17,CTLA-4 and PD-1 were detected by flow cytometry(FCM) after intracellular and surface membrane staining. Results The proportions of Th17 cells was higher while that of Th2 cells was lower in PTB,EPTB and LC patients than in HS.However,no significant difference was found in the proportions of Th1 cells between PTB,EPTB,LC patients and HS.The ratio of Th1/Th17 cells and the ratio of Th2/Th17 cells were lower in PTB and EPTB patients than in HS.The proportions of CTLA-4⁺ CD3⁺ T cells was higher in EPTB patients than in PTB,LC patients and HS.The proportions of PD-1⁺ CD4⁺ T cells was higher in PTB and LC patients than in HS.The proportions of CTLA-4⁺ CD3⁺ T cells was negatively associated with that of Th1 cells in PTB patients,while the proportions of PD-1⁺ CD4⁺ T cells was positively associated with that of Th17 cells in EPTB patients(r=-0.48,P=0.014;r=0.68,P=0.015). Conclusion The proportions of Th17 cells increases in active TB patients.