To sum up, a suggested explanation is that OPN is highly expressed by activated immune cells during the MTB infections, in addition, it also co-stimulates T cell proliferation in the setting of T cell activation and induces the expressions of Th1 but not Th2 cytokines like IL-2, IFN-γ and TNF-α in macrophages and T cells, helping to recruit immune cells to the site of tuberculous lesions and mediate phagocytosis of macrophages and granuloma formation [13, 42]. This evidence concerns the gene SPP1 and Granuloma.