Filter allows kidney transplant without matching recipient, donor blood type.

A new blood filter could significantly increase the number of living donor kidney transplants by facilitating transplantation between people of different blood types.

Gunnar Tyden, MD, a professor of transplantation surgery at Huddinge University in Stockholm, Sweden said the new device allowed a 20-year-old patient with type O blood to receive a kidney donated by her father, who has type A blood. "The patient is doing excellently," Tyden reported. "She has gone past the danger period. If nothing has happened so far, then nothing probably will."

Tyden performed the surgery 6 weeks ago using a filtering device called GlucoSorb, manufactured by the Swedish company Glycorex Transplantation AB. The filter, expected to reach the market in months, works by removing blood group antibodies directed against the donor graft. Nonspecific antibody removal techniques, such as plasmapheresis, have been used previously. But kidney transplants involving plasmapheresis often are accompanied by splenectomy, which is harmful to patients.

To prevent the patient from producing antibodies to the donor's blood group, Tyden administered the monoclonal antibody rituximab. So far, it is working, and there are no complications. Tyden acknowledged that rituximab adds another drug to the immunosuppressive regimen, possibly increasing the risk of infection. "But there's been no problem with the filtration of blood," he said.

Tyden plans to perform another kidney transplant using the filtering device "as soon as possible," noting that many people who previously were denied a transplant are hoping they now qualify. In Sweden, 500 patients are on the kidney transplant waiting list. Every year, 300 such transplants are performed, 100 from living donors.

"This opens the possibility for willing and potential donors who don't have the same blood type as the kidney patient," said Tyden. "Now, a husband can donate to his wife, a father, to his daughter, even if they have different blood types. This could double the number of kidney transplants from living donors."