CD8 refers to leukocyte differentiation antigen. If CD8 is high after kidney transplantation, it means there is some rejection reaction. There are many reasons for the rejection reaction of kidney transplantation, such as insufficient drug concentration, strong resistance of human body, improper way of taking drugs and so on. 1. Insufficient drug concentration: Insufficient concentration of drugs to inhibit cellular immunity such as anti-lymphocyte globulin and monoclonal anti-T-cell antibody will lead to the aggravation of the rejection reaction, which will lead to the phenomenon of high CD8 after kidney transplantation. 2. The human body is more resistant to drugs: if the patient due to personal physical reasons lead to anti-rejection drugs can not inhibit the destruction of the transplanted kidney by autoimmune cells, it will lead to high CD8 after kidney transplantation. 3. Improper way of taking medication: if patients do not take medication according to the doctor’s instruction after kidney transplantation or the medication itself has problems, it may not be able to inhibit the destruction of the transplanted kidney by the immune system, which will lead to high CD8 after kidney transplantation. If there is swelling and pain in the transplanted area, and the urine test shows increased protein, high CD8, and elevated white blood cells in the urine, it means that rejection reaction may occur, and treatment measures should be taken as soon as possible. Therefore, patients should cooperate with medical personnel to find out the cause of the disease, and then take step-by-step treatment. High CD8 after kidney transplantation is a common situation, and it is recommended to analyze the urine test data in time and then take targeted treatment.