Cytotoxic T-cells, also known as cytotoxic T lymphocytes, are a kind of specific killer T-cells, which are involved in the body’s immune function; high cytotoxic T-cells indicate that the body may have viral infections or neoplastic diseases, etc., but a single test item cannot indicate a specific disease. 1. Viral infections: common viral infections such as viral colds, chicken pox, measles, etc., the target cells are infected by viruses and the molecules on the surface of the cells change, the cytotoxic T cells recognize this signal and destroy the virus-infected cells, which is manifested as high cytotoxic T cells. 2. Tumor disease: when patients have lymphoma, leukemia and other diseases, cytotoxic T cells are activated to participate in the immune response, gather to the tumor site, and secrete effectors to selectively kill the target cells; a high cytotoxic T cell phenomenon occurs. A single abnormal test result can not be used as the basis for the diagnosis of the disease, but should be combined with the patient’s condition and other auxiliary examination results to make a comprehensive judgment; find the abnormal test results or physical discomfort and consult a doctor in time to avoid delaying the treatment.