Objective:To explore the expression and clinical significance of immunosuppressive receptor T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) on the peripheral blood mononuclear cells (PBMC) in silicosis patients with Mycobacterium tuberculosis infection. Methods:August 2018, a total of 78 patients with silicosis (all were quarry workers in Sanmen County, Zhejiang Province) were enrolled and divided into silicosis combined with active pulmonary tuberculosis group (APTB group), silicosis combined with latent tuberculosis infection group (LTBI group), and simple silicosis with non-tuberculosis infection group (non-TB group). Flow cytometry was used to analyze the expressions of TIGIT, programmed death-1 (PD-1) and transcription factor T-bet on PBMC from patients. Mann-Whitney U test and Pearson correlations analysis were used for statistical analysis. Results:Among the 78 patients, eight were in the APTB group, 24 in the LTBI group, and 46 in the non-TB group. The expressions of PD-1 and TIGIT on CD8 + T cells in the APTB group (29.45%(16.78%) and 65.40%(12.12%), respectively) were significantly higher than those in the LTBI group (17.40%(11.17%) and 48.30%(28.75%), respectively; U=23.500 and 43.500, respectively, P=0.000 8 and 0.020 5, respectively) and non-TB group (15.95%(12.46%) and 45.30%(19.75%), respectively; U=64.000 and 69.000, respectively, P=0.002 3 and 0.003 8, respectively), and the differences were all statistically significant. The expression of TIGIT was positively correlated with PD-1 on CD8 + T cells in silicosis patients ( r=0.434 3, P<0.01). The proportion of PD-1 + TIGIT + CD8 + T cells in the APTB group (19.90%(22.67%)) was significantly higher than those in the non-TB group (11.55%(11.29%), U=76.500, P=0.007 1) and LTBI group (11.55%(10.53%), U=41.000, P=0.015 4), while the proportion of PD-1 -TIGIT -CD8 + T cells in the APTB group (30.60%(12.90%)) was significantly lower than non-TB group (48.90%(18.98%), U=58.000, P=0.001 3) and LTBI group (47.20%(24.59%), U=41.000, P=0.015 4). The differences were all statistically significant. The expression of T-bet on the peripheral blood CD8 + T cells in the APTB group (29.45%(16.78%)) was higher than that in the non-TB group (15.95%(12.46%)) and the LTBI group (17.40%(11.17%)), and the differences were both statistically significant ( U=46.500 and 46.000, respectively, P=0.000 3 and 0.028 3, respectively). The expression of T-bet on CD8 + T cells was positively correlated with TIGIT on CD8 + T cells ( r=0.456 7, P<0.01). The expression of T-bet on PD-1 + TIGIT + CD8 + T cells in the APTB group (65.40%(12.12%)) was higher than those in the LTBI group (48.30%(28.75%), U=23.500, P=0.000 8) and non-TB group (45.30%(19.75%), U=65.000, P=0.002 6), and the differences were both statistically significant. Conclusion:The immunosuppressive receptor PD-1 and TIGIT are highly expressed on CD8 + T cells in silicosis patients with active pulmonary tuberculosis, which indicates CD8 + T cells exhaustion in these population, while the highly co-expression of T-bet suggests the exhausted subsets may have reversed potentiality.