The Observation Of Peripheral CD8～+CD28～-T Lymphocytes In Allograft Renal Transplantation Recipients

ObjectiveAdvances in past decades have greatly improved patient outcomes following organtransplant. However, generalized immunosuppression remains the most importantfactor that affect the long-term survival of patients and grafts. Tolerance is theultimate goal. CD8~+CD28~-T suppressor which generated from peripheral CD8~+CD28~-T cell shows its potential in inducible antigen-specific immunotolerance. Our study isto try to explore the fluctuations in peripheral CD8~+CD28~-T lymphocytes level and itscorrelation with graft function in renal transplant recipients.Methods(1) 30 random renal transplant recipients were screened the presence of peripheralCD8~+CD28~-T lymphocytes by flow cytometry 1 week before transplantation and 2, 8,24 weeks after transplantation respectively. All cases received tripleimmunosuppression with cyclosporine A, mizoribine and methylprednisolone orprednisone, two cases receive ATG from the day 1 to day 3 after transplantation. 20healthy peoples were also tested for the level of peripheral CD8~+CD28~-T lymphocytesas control.(2) A group of 25 allograft renal transplant recipients, who were 6 months to 30months after operations and with abnormal serum creatinine (＞133μmol/L) andanother group of 25 renal transplant recipients with normal serum creatinine (≤133μmol/L) were matched in age, gender, time after transplantation and the regimenof immunosuppression. All cases received triple immunosuppression either withcyclosporine A, mizoribine and prednisone or with tacrolimus, mycophenolatemofetil and prednisone. Both groups were tested for the percentage of CD8~+CD28~-Tlymphocytes in peripheral blood lymphocytes by flow cytometry.Results(1) the percentage of peripheral CD8~+CD28~ T lymphocytes were not different between helthy peoples and patients before transplantation (P＜0.05).(2) The frequencies of CD8~+CD28~-T lymphocytes show up an ascending trend aftertransplantation among 30 random tansplant recipients. There were statisticallysignificant differences between preoperation, week 8 and week 24 postoperation(P＜0.05), while no statistically significant difference existed between preoperationand week 2. A negative correlation was observed between the level of serumcreatinine and the level of peripheral CD8~+CD28~-T lymphocytes in week 24 aftertransplantation(r=-0.539, P＜0.01).(3) The percentage of CD8~+CD28~-T lymphocytes in the group with abnormal serumcreatinine (16.62%±3.34% ) is obviously lower than in the group with normal serumcreatinine (20.91%±7.68%).Conclusion(1) the level of CD8~+CD28~-T lymphocytes rises after transplantation. PeripheralCD8~+CD28~-T lymphocytes have the activity of Ts cell and are protective factor ofgraft function.(3) CD8~+CD28~-T lymphocytes could be a usable index in predicting prospective graftfunction in renal transplant recipients and may be a clue that will help achieveinducible immune tolerance.