When the immune function of human body decreases, the mutated cells in the body cannot be removed in time and human body is prone to tumor. What happens when the immune function of human body will be low 1, the age factor: after young and strong age, as the body grows older, the organs of human body, including immune system, are gradually worn out, and the immune function is also gradually reduced, and various tumors also occur 2, environmental pollution: including air, water, food, noise pollution, research found that environmental pollution can not only directly lead to the mutation of cells in the body, but also can seriously damage the immune system. It can also seriously damage the body’s immune system. 3, viral infection: one of the reasons why AIDS patients are prone to tumors is their low immunity, and many viruses can damage the body’s immune system. 4, mental stress: everyone may have such experience, when stressful, may occur oral herpes or prone to cold, oral herpes and cold are mostly viral infections, which means your cellular immune function is very low, at this time, your immune cells can not effectively remove the mutated cells. 5.Nutritional status: When malnutrition, immune function is prone to damage Therefore, in order to avoid the occurrence of tumor, we should first protect our immune system, stay away from pollution, combine work and rest, reasonable work and rest time, and maintain a healthy nutritional status.