[Th1 immune response induced by Mycobacterium tuberculosis H37Ra in NOD2 knockout mice]

Objective To investigate the roles of Th1 cytokines tumor necrosis factor α (TNF-α), interferon gamma (IFN-γ) and multifunctional T cells in nucleotides binding oligomer domain 2 knockout (NOD2^-/-) mice infected with Mycobacterium tuberculosis (MTB) H37Ra. Methods Mouse models of pulmonary infection were established by tracheal instillation of MTB strain H37Ra into NOD2^-/- mice and C57BL/6 mice (n=10 each group). Lung tissues were removed and stained by HE staining and pathological scores were evaluated 4 weeks after infection. The levels of TNF-α and IFN-γ in the lung homogenates were detected by ELISA, and the ratio of multifunctional CD4⁺ T and CD8⁺ T cells in the spleen were examined by flow cytometry. Results MTB infection promoted lung inflammation of NOD2^-/- mice. The levels of TNF-α and IFN-γ in the lung tissues of NOD2^-/- mice increased. Compared with normal saline group, TNF-α⁺, IFN-γ⁺ cells and TNF-α⁺IFN-γ⁺ cells in CD4⁺/CD8⁺T cells significantly increased in NOD2^-/- mice and C57BL/6 mice after the infection. TNF-α⁺CD4⁺T cells, IFN-γ⁺CD4⁺T cells and IFN-γ⁺CD8⁺T cells in MTB-infected NOD2^-/- mice were significantly higher than those in MTB-infected C57BL/6 mice. Conclusion H37Ra can induce Th1 immune response in NOD2^-/- mice.