Dynamic Changes of Regulatory T Cells/CD4⁺ T Cells in Peripheral Blood of Adult Kidney Transplant Recipients: A Comparison of Pediatric and Adult Kidney Donors

Abstract

BACKGROUND Inducing transplantation tolerance and monitoring the recipient's immune status to improve allograft survival remains the main goal for kidney transplantation (KTx). MATERIAL AND METHODS A total of 53 renal transplantation patients and 20 healthy individuals were assigned to the post-transplantation and healthy groups, respectively; 10 recipients with stable renal function for 2 years after kidney transplantation were assigned to Group C. Eleven kidney transplantation recipients were hospitalized due to lung infection. Flow cytometry was used to measure levels of Tregs/CD4⁺ T cells. RESULTS The Tregs/CD4⁺ T cells ratio reached homeostasis 6 months after KTx, with no significant difference between Group D (healthy control group) and pre-surgery or Group C (2 years after KTx group). The pediatric donor group and the adult donor group reached immune homeostasis 3 months after the operation. Immune homeostasis is maintaining a balance between immune tolerance and immunogenicity. There was no significant difference in graft function between the pediatric and adult donor groups before surgery, 1 day after surgery, 1 week after surgery, 2 weeks after surgery, and 1 month after surgery; however, graft function was significantly better in the pediatric donor group compared with the adult donor group at 3 mouths (eGFR: 51.7 (40.4-66.2) vs 73.0 (55.7-90.2), P=0.008<0.05) and 6 months (eGFR: 52.2 (37.5-62.8) vs 80.5 (64.1-90.4), P<0.001) after surgery. Pediatric donor kidneys reached immune homeostasis 3 months after surgery, with better graft function at this time compared with adult donor kidneys. The proportion of Tregs/CD4⁺ T cells in recipients with a pulmonary infection after KTx was lower than in those with infection recovery. CONCLUSIONS Expanding the use of pediatric kidneys should be further explored by the transplantation community. The proportion of Tregs/CD4⁺ T cells in recipients with a pulmonary infection after KTx was lower than in those with infection recovery.

Figure 1

Flow cytometry gating strategy. The lymphocyte population was selected based on FSC/SSC scatters: (a) CD4⁺ lymphocytes dot plot; (b) CD127 vs CD25 dot plot of CD4⁺ lymphocytes. D0: the day before KTx, D1: the first day after KTx, W1: the first-week after KTx, W2: the second-week after KTx, M1: the first month after KTx, M3: the third month after KTx, M6: the sixth month after KTx. Group C: 2 individual kidney recipients with stable renal function for 2 years after kidney transplantation. Group D: 2 healthy individuals.

Figure 2

Dynamic changes of Tregs-to-CD4⁺ T cells ratio.

Figure 3

The Tregs-to-CD4⁺ T cells ratio of groups C and D.

Figure 4

Dynamic changes of lymphocyte count.

Figure 5

The Tregs/CD4⁺ T cells ratio at various time point between kidney recipients from pediatric and adult donors.

Figure 6

The level of Tregs/CD4⁺ T cell in infection and infection recovery.