Background: Tuberculosis infection is a major complication of silicosis but there is no study on whether the silicosis can affect the sensitivity of QuantiFERON-TB Gold In-Tube (QFT-GIT) assays. This study will analysis the relationship between silicosis and QFT-GIT, figure out the main factor of the QFT-GIT sensitivity decrease in silicosis and exploring the methods to increase the sensitivity.Methods: Silicosis patients with positive tubercle bacillus cultures were collected. The QFT-GIT, flow cytometry and blocking antibodies were used. Results: The sensitivity of QFT-GIT in silicosis patients(58.46%) was significantly decreased and the expression of PD-1 on T cells and CD56+NK cells in pulmonary tuberculosis combined with silicosis were higher than normal tuberculosis patients. Further analysis found that the ratio of PD-1+CD4+T and IFN-γwere negatively correlated and blockaded the PD-1 pathway with antibodies can restore the sensitivity of QFT-GIT in silicosis.Conclusions: This is the first study which analysis the relationship between the immune exhaustion and QFT-GIT in silicosis and found the sensitivity of QFT-GIT was decreased by the expression of PD-1 on lymphocytes. Antibody blocking experiments increased the expression of IFN-γ and provide a new method to improve the sensitivity of QFT in silicosis. The study also found silicosis can increased the PD-1 expression, as the PD-1 function in infectious diseases, it will promote the immune exhaustion in silicosis and lead the tuberculosis from latent infection to active. The study provided theoretical evidence for the diagnosis and immunotherapy of silicosis complications, and it has great value in clinical diagnostics and treatment.
