The purpose of this study was to explore the accuracy of sentinel skin grafts from the same donor source in diagnosing renal allograft rejection, and to provide new ideas and options for the later clinical diagnosis of renal allograft rejection. Further, try to provide timing guidance for early immunization intervention.

Inclusion Criteria:

1. Patients with end-stage renal disease undergoing renal transplantation;
2. 18-60 years old;
3. Postoperative follow-up points are complete (visit the hospital every week in the first month after surgery, every two weeks in 2-3 months, every four to six months, and every three months in 7-12 months. Follow up at any time when skin rejection is observed. The follow-up time may be adjusted when the condition changes);
4. The participants had good compliance, volunteered to participate in the test and signed the informed consent form.

Exclusion Criteria:

1. Untreated or disseminated malignant tumor;
2. Active period of infectious diseases;
3. Serious cardiovascular disease occurred recently;
4. Combined with other important organ failure;
5. History of mental illness or cognitive impairment;

This study is an exploratory study. In the early stage, there is no relevant study on the accuracy of sentinel skin flap monitoring renal rejection, and there is a lack of corresponding sensitivity and specificity indicators. Considering that the incidence of acute rejection in the first year after transplantation is 15-30%, it is estimated that 20 cases will be included. Because the experimental data may be lost, or the participants may withdraw from the trial or lose the interview, the sample size will be increased by 20%, and finally 24 cases will be included in the trial.