Immunotherapeutical potential of Mycobacterium vaccae on M. tuberculosis infection in mice

Tuberculosis remains the worldwide infectious disease. To identify the therapeutic potential of M. vaccae in treating tuberculosis, M. vaccae was injected into Mycobacterium tuberculosis (M. tuberculosis) infected mice. The optimal dose of M. vaccae (22.5 microg/mouse) treated mice showed lower pathological change index, spleen weight index, lung weight index and vital M. tuberculosis count than those of the untreated group. Treatment with M. vaccae enhanced the percentages of CD3+ and CD4+ T cells, IFN-gamma+CD4+ T cells, innate immune cells including NK cells, NK1.1+ T cells and gammadeltaT cells, and reduced the percentage of IL-4+CD4+ T cells. Therefore, M. vaccae could protect the mice from M. tuberculosis infection and improve mouse innate and adaptive cell-mediated immunity, suggesting that M. vaccae is a potential immunotherapeutic agent in pulmonary tuberculosis.