A Significant Expansion of CD8+ CD28- T-Suppressor Cells in Adult-to-Adult Living Donor Liver Transplant Recipients

Background. The appearance of human regulatory CD8(+) CD28(-) T-suppressor (Ts) cells has been associated with a reduced need for maintenance immunosuppression in cadaveric heart- kidney transplant recipients and pediatric liver-intestine transplant recipients. However, few data are available in adult-to-adult living donor liver transplantation (A-A LDLT). Materials and Methods. To study the population of CD8(+) CD28(-) Ts cells in A-A LDLT, we performed flow cytometry on whole blood specimens obtained from 20 transplant recipients, 18 end-stage liver disease patients, and 20 normal controls. Meanwhile, we measured the trough levels of immunosuppressants and monitored graft function in transplant recipients. We retrospectively reviewed the clinical data of the 20 recipients. Results. A significant expansion of CD8(+) CD28(-) Ts cells was observed among recipients of A-A LDLT as compared with a disease control group (P = .000) or healthy individuals (P = .000). All recipients were free of acute cellular rejection episodes. During the follow-up period, no grafts were lost due to acute or chronic rejection. Conclusion. Expansion of CD8(+) CD28(-) Ts cells in A-A LDLT seemed to be associated with a decreased occurrence of acute or chronic rejection and sustained good graft function. Based on our low dosages of immunosuppressants for recipients of A-A LDLT, we suggest that this strategy may promote expansion of CD8(+) CD28(-) Ts cells, which can conversely maintain the low immunosuppressant dosages.