T-lymphocytes (CD4+), which are among the most important immune cells of the entire defense system, have the ability to differentiate into other T-lymphocytes such as CD8+ and regulatory T-cells (Tregs) in TME in a variable and cytokine-dependent manner, making this interaction a critical factor in slowing tumor growth and providing a good prognosis for patients [236, 237]. The gene discussed is CD8A; the disease is neoplasm.