UW Desensitization Program Provides Option for Live Kidney Donors
News for Referring Physicians
To learn more about desensitization, or to speak with program advisors, please call (608) 261-1653.
Up to 30 percent of patients awaiting kidney transplant are considered sensitized - having preformed antibodies to potential donor antigens. These antibodies can be developed in individuals through previous exposure to foreign tissues via transplantation, blood transfusion or pregnancy.
A patient is considered sensitized when the Panel Reactive Antibody (PRA) is greater than 20 percent. The sensitivity can be based on blood type or tissue.
Desensitization is a process that removes these harmful antibodies from the bloodstream of patients and/or prevents their production.
Sensitized patients face two major problems: difficulty finding a suitable donor and the high risk of acute rejection once they receive the transplant. They may wait three to four times longer for a compatible deceased donor kidney than a patient who is non-sensitized.
Aji Djamali, MD, director of nephrology research, recently became the director of the University of Wisconsin Hospital and Clinics desensitization program. He states that the role of the desensitization program is to "address these problems by preparing patients to receive a kidney transplant from a live or nonliving donor even if they are sensitized."
Most patients entering the desensitization program have a live kidney donor. In addition, there are protocols for patients who are waiting for a nonliving donor. The program is designed to "tailor the patient's immunosuppression to minimize the risk of acute rejection."
The desensitization process begins with plasmapheresis treatments. The number of treatments depends on the level of harmful antibodies present in the blood. Typically patients receive three or four treatments prior to transplant. Along with plasmapheresis, patients receive immmunosuppresant medications. In some cases, plasmapheresis treatments may be necessary after transplantation to reduce the risk of rejection.
"As a result of sensitization," says Dr. Djamali, "some patients are destined to remain on dialysis despite having live donors available. Desensitization protocols provide an opportunity for these patients to receive a kidney transplant."
The UW Health desensitization program began in 2004. As a result, 48 highly-sensitized patients have had successful kidney transplantations, including eight ABO incompatible transplants.
In early 2009, Dr. Djamali says the team "developed novel desensitization protocols based on state-of-the-art Single Antigen Bead Luminex Assay Technology. This solid-based assay complemented our standard cell-based assays including cytotoxic T cell cross match."
They then designed five protocols to tailor immunosuppressive strategies based on the intensity of sensitization against the donor. These treatment protocols combine plasmapheresis, monoclonal antibodies (rituximab) and polyclonal antibodies (thymoglobulin and intravenous immunoglobulins), and maintenance immunosuppression with tacrolimus, mycophenolic acid and prednisone.
Using these new protocols, the UW Health transplant team has successfully transplanted more than 30 patients in 2009. Future plans include the use of novel immunosuppressive drugs to offer treatment options for patients who cannot be desensitized using current protocols.
Dr. Djamali points out that not all desensitization protocols are successful. The failure rate is about 20-30 percent, and depends on the level and type of preformed antibodies present in the patient.
"Nevertheless," he adds, "the UW Hospital and Clinics desensitization program offers options for ABO-incompatible and highly-sensitized HLA incompatible kidney transplantation to patients who have a live donor."
Dr. Djamali says he has a deep appreciation for the desensitization team at UW Hospital and Clinics.
"Successful transplantation in a sensitized patient represents hundreds of hours of detailed work from our HLA laboratory technicians and manager, our transplant coordinators, nurse practitioners, physicians and surgeons," he says. New treatment strategies and therapeutic options emerge and the team has to adjust.
"Although the implementation of the protocols has been of some help," Dr. Djamali adds, "the greatest recognitions should go to this wonderful team of committed and talented people."