Treatment of Children With Kidney Transplants by Injection of CD4+CD25+FoxP3+ T Cells to Prevent Organ Rejection

Overview

T regulatory cells (T regs) are responsible for immune tolerance in solid organ transplant patients. This study will evaluate the treatment of children with kidney transplants either with Campath and other immune system suppressing medications alone or in combination with injection of autologous CD4+CD25+CD127lowFoxP3+ T regulatory cells expanded ex vivo. The aim of this study is to develop a new strategy that will be more effective in preventing organ rejection and maintaining patient health.

Kidney transplantation is a common procedure in hospitals, but organ rejection and serious side effects are potential problems for patients. Alemtuzumab is a monoclonal antibody to CD52 that binds to and depletes excess of T cells in the bone marrow of leukemia patients. In this study alemtuzumab will be used to deplete the recipient's white blood cells (WBCs) at the time of transplantation. An experimental group of patients will receive two injections of autologous CD4+CD25+CD127lowFoxP3+ T regulatory cells expanded ex vivo at day 30 and day 180 after transplantation. T regulatory cells are responsible for immune system tolerance induction. Treatment with these cells is believed to create tolerance when T cell immune responses to transplant alloantigens are decreased. This study will evaluate the safety and effectiveness of an antirejection regimen including alemtuzumab and other immunosuppressive medications combined with autologous T regs injections in patients undergoing kidney transplantation (Tx). Patients will receive i.v. injection of alemtuzumab on Days 14-21 before Tx and on Day 0. Starting on Day 0, patients will begin taking either tacrolimus or cyclosporine, and on Day 2-3 - mycophenolate mofetil. This study will continue during three years. Participants will be randomly assigned to receive either the full immunosuppressive therapy and autologous T regs by s.c. injection (group 1) or immunosuppressive therapy alone (group 2). Prior to immunosuppressive therapy in the group 1, blood samples will be collected twice with at least one-week interval between collections in the amount of 70 ml/1,73 m2 . Two ml of blood will be collected before starting of immunosuppressive therapy and levels of T regs in periphery blood will be examined by flow cytometry analysis in both groups. T cells CD4+ will be separated from these blood samples and will be frozen in liquid nitrogen. All patients will undergo kidney transplantation. One month after transplantation the flow cytometry analysis of blood samples will be performed in both groups. The patients in group 1 will undergo by subcutaneous injection of approximately 2x10\^8 autologous T regs expanded from previously frozen CD4+ cells in a month and 180 days after transplantation. One week following the injection, an additional flow cytometry analysis will be performed to evaluate T reg levels in patient's blood. The level of T regs in patient's blood will be repeated in both groups after 90-120 days following transplantation. Patients will be monitored during three years post-transplantation. Urine samples will be collected after one week and 1, 3, 6, and 9 months following transplantation. Kidney biopsy will be performed at Months 1, 12, and 36. Based on results of biopsy analysis, kidney function and signs of over-immunosuppression, some patients will be switched from CNIs (calcineurin inhibitors, tacrolimus or cyclosporine) to PSIs regiment (sirolimus or everolimus).