Easier Rules for Kidney Transplants Urged
NORRIS: From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.
MELISSA BLOCK, host:
And I'm Melissa Block.
It used to be that people would wait years for a kidney transplant because a tissue match donor could not be found. In the past decade, that's been changing. The waits are still long, but the need for a perfect tissue match has decreased.
NPR's Joe Palca explains why.
JOE PALCA reporting:
When people talk about tissue matching for organs, they mean finding out if donor and recipient have the same HLA.
Ms. KAREN NELSON (Puget Sound Blood Center): HLA are proteins that occur on the surface of all the cells in our bodies.
PALCA: Karen Nelson is the director of the Immunogenetics/HLA Laboratory at the Puget Sound Blood Center in Seattle. HLA comes in a number of types, and each of the types has a number of flavors. That's why finding exact matches is so difficult.
The HLA proteins tell our immune systems what belongs to us and what doesn't. Our immune system is constantly checking cells, like a posse of patrolling night watchmen. As long as cells have the right HLA proteins, they can go about their business.
Ms. NELSON: But proteins from somebody else's individual cells, when our immune system sees those, they recognize those as foreign and actually interpret them as maybe being diseased or dangerous, and can attack them.
PALCA: Given that, what do you suppose would happen if you took a donor kidney and put it into an unmatched recipient?
Mr. JOHN ROBERTS (University of California, San Francisco): It would blow out.
PALCA: John Roberts is chief of transplants at the University of California, San Francisco. Blow out isn't the precise technical term, but Roberts says it gives a pretty good idea of what would happen.
Mr. ROBERTS: You'd probably get five days or a week, and then what happens is that the body recognizes that it's foreign and jumps all over it.
PALCA: Now if two people have precisely - and I mean precisely - the same genetic makeup, and therefore precisely the same HLA, then you don't have to worry about rejection. That's why the first successful kidney transplant was done between identical twins.
But nearly always, there's some mismatch, so doctors use drugs to suppress the immune system so it won't jump all over the foreign kidney. And over the past decade, those drugs have gotten much better. So Roberts did a little study of kidney transplants to see whether abandoning HLA matching led to a worse outcome.
Mr. ROBERTS: It looks like it's not a lot worse, if anything worse. If you look at it with thousands of people, you can still see a difference, but the difference has been getter smaller and smaller over time.
PALCA: But this may be a case of what you see depends a little on what you're looking for. Roberts compared recipients who were tested for HLA and those who weren't. But HLA matching isn't all or nothing. There's a range from perfect to terrible, with lots of steps in between. Karen Nelson says when you look at how good the match is, you see evidence that well-matched patients do better.
Ms. NELSON: We found that their kidneys are surviving and functioning 50 percent longer when we compare them to individuals who did not get these well-matched kidneys.
PALCA: That could be the difference between a kidney that lasts 10 years and one that lasts 15. And that raises the question of why, with time, even well-matched kidneys fail. Connie Davis is director of the kidney and pancreas transplant program at the University of Washington. She says that's a good question.
Ms. CONNIE DAVIS (University of Washington): The immune system matures and the responses mature with time against the transplant, and it's this part of the process that we haven't really figured out.
PALCA: Figuring it out will be important, because kidneys available for transplant are a precious commodity.
Joe Palca, NPR News, Washington.