Highly Sensitized Patients
The Montefiore Einstein Center for Transplantation now performs kidney transplants on patients with circulating antibodies, previously a reason for transplant ineligibility. This is accomplished through a special process called desensitization.
Questions and Answers About Antibodies and Sensitization With Kidney Transplantation
Q. What does sensitized mean?
A. Approximately30 percent of patients who are waiting for a donor kidney are considered sensitized, which means they have exceptionally high antibody levels that react to foreign tissue. High antibody levels are harder to match for donor kidneys. People develop this type of antibody through a previous exposure to foreign tissue, such as a prior transplant, blood transfusion or pregnancy. In fact, each year only 6.5 percent of highly sensitized patients receive a transplant. Sensitized patients wait three to four times longer than unsensitized patients for a compatible deceased donor.
Q. How do I know that I am sensitized?
A. Panel reactive antibody (PRA) measures antihuman antibodies in the blood. The PRA score is expressed as a percentage, which can range from 0 to 99 percent, that represents the likelihood of your blood having an antibody against a particular donor. A PRA of 20 percent means you have antibodies to approximately 20 percent of the population. Having antibodies against foreign tissues makes it difficult to find a compatible living or deceased donor kidney.
Q. How long does the desensitization protocol continue?
A. The number of treatments a patient needs is determined by the level of harmful antibodies present in a patient's blood. These levels are checked frequently to determine if additional treatments are needed. At least four plasmapheresis treatments are required prior to transplant. Intravenous immunoglobulin (IVIG) is given once during one high definition (HD) session after four sessions of plasmapheresis. If the antibody levels do not decrease sufficiently, we do an additional four sessions of plasmapheresis and one more IVIG infusion.
Q. Do I need a live kidney donor for the desensitization program?
A. Live donor candidates with a donor organ receive desensitization treatments. Through desensitization, or removal of antibodies from the blood, immediately before the transplant, the organ is successfully transplanted into a sensitized patient. Patients may also receive desensitization if they are sensitized and have waited more than five years on the donor list. By treating the patient with immunoglobulin and Rituximab, the sensitized patient's antibody levels are decreased. Only sensitized patients testing negative for antibodies in the blood receive transplants.
Q. What is a donor cross-match test?
A. The most important test in kidney donation is the cross-match test. It involves mixing blood from the recipient with blood cells from the donor. The cross-match test should be negative, meaning there are no antibodies present that would work against the donated organ, in order to do the transplant. A positive result shows that harmful antibodies are present that would work against the donor, meaning the kidney would be rejected immediately.
Q. What are the options if my cross-match is positive?
A. There are three options if you have a positive cross-match: wait for another donor who has a negative cross-match, participate in a donor exchange program or undergo the desensitization process.
Q. What is the success rate of desensitization? Am I at higher risk to develop rejection after transplantation?
A. Currently, one-year graft survival in unsensitized living donor recipients in the United States is 96 percent. One-year graft survival in sensitized patients is around 90 to 92 percent. The rejection risk in sensitized patients is 20 to 25 percent, which is higher than in unsensitized patients (10 to 15 percent).
Q. What are the costs of desensitization?
A. Patients who go through the desensitization program can expect an additional $20,000 to $30,000 above the cost of a kidney transplant that does not require desensitization. Some insurances cover the additional costs. Before any steps are taken in the desensitization process, our financial adviser meets with patients to discuss their insurance coverage.