The Positive Crossmatch and | Incompatible Kidney Program |
Are you Sensitized?
If you are, you are not alone. About 30 percent of patients waiting for kidney transplants are considered sensitized. Sensitized patients have developed harmful antibodies in their blood against foreign tissue. A person can develop antibodies through previous exposure to foreign tissue resulting from pregnancies, previous transplants, or blood transfusions. Sensitized patients may wait three or four times longer than unsensitized patients for a compatible deceased donor kidney.
What is a Positive Crossmatch?
The level of harmful antibody is quantified by panel reactive antibodies or PRA. A potential recipient who has a PRA greater than 30 percent is considered sensitized. Many sensitized patients have live donors willing to give them a kidney, but the transplant has little chance of success. When the recipient’s blood is mixed with the donor’s blood (a test called a crossmatch), the sensitized recipient’s antibodies react against the donor’s cells. This is called a positive crossmatch, which means the recipient probably will reject the kidney immediately following transplant. A negative crossmatch is needed between the recipient and the donor prior to the transplant.
If the antibodies in the recipient’s blood can be removed prior to the transplant and be prevented from coming back, a successful live donor transplant is possible. To do this, physicians and scientists at The Johns Hopkins Hospital have developed a protocol to remove harmful antibodies from patients who have a Positive Crossmatch and are Sensitized to their live donor.
What does the treatment involve?
As in the blood type incompatible program, sensitized patients undergo plasmapheresis treatments to help remove harmful antibodies from the blood. On average, patients receive about four treatments before the transplant but the actual number required is determined by the level of harmful antibodies in the recipient’s blood. An intravenous infusion of immune globulin is given after each plasmapheresis treatment to help prevent harmful antibodies from coming back after the transplant. Recipients undergo plasmapheresis and immune globulin treatments every other day starting one to two weeks prior to the transplant. For example, if the number of treatments needed is four, the recipient begins plasmapheresis eight days prior to the transplant. The recipient receives these treatments on an outpatient basis without disruption of their dialysis schedule.
Do harmful antibodies return and damage the new kidney?
After the transplant, recipients have several additional plasmapheresis treatments, followed by intravenous immune globulin, to prevent harmful antibodies from coming back. The level of antibodies in the recipient’s blood is checked frequently following the transplant to determine if more plasmapheresis treatments are needed. After all the plasmapheresis treatments are completed, these patients receive the same medications as any other transplant patients.
