Expression of tumor immune cells Among the tumor immune effects is mainly cellular immunity, where T lymphocytes play a central regulatory role in tumor immunity. Tumors affect immune cells such as T lymphocytes, NK cells, macrophages, and K cells. CD system antigens exist on the surface of normal T cells, of which CD3 is the fully mature T cells and the ratio is constant in human body. CD4 is the helper T lymphocytes and CD8 is the suppressor T lymphocytes in the two subsets of immune system to maintain the optimal balance of immune system in the body and play the role of cellular immune surveillance. NK cells and T cell subsets play an important role in tumor immunity. Disturbed T cell subsets are often seen in the peripheral blood of tumor patients, as evidenced by decreased CD3, CD4 and CD4/CD8 ratios. When the tumor load is relieved, the disturbed T-cell subsets are gradually restored. Thymidine modifies the disorder of the immune system, resulting in increased CD4 percentage, decreased CD8, and normal CD4/CD8 levels after administration of the drug.