Every year, 4,500 Americans die waiting for a kidney transplant. It’s not just because there aren’t enough donors—part of the problem is that donors need to be compatible to prevent the recipient’s body from rejecting the new kidney. They need the right blood type, but they also have to have the right combination of six antigens–molecules on a cell that have the capacity to trigger an immune response. Any two random people have a one in 100,000 chance that all six antigens will match, and even then it’s not a guarantee that the kidney won’t be rejected.
Fifteen years ago, researchers from the Johns Hopkins University School of Medicine started developing a technique to quiet the recipient’s immune system, making even incompatible donors a match. Now, after an eight-year study and evaluating thousands of patients, they have proof that this immune-quieting method works better than the alternatives and is saving lives, which could make it more widespread. The researchers published a study today in the New England Journal of Medicine.
In patients whose immune systems would actively combat a transplant, doctors perform a technique called desensitization, in which they filter antibodies from the patient’s blood. The new antigens that the body regenerates to replace them are less likely to attack a transplanted organ, though no one is quite sure why, as the New York Times reports.
This immune-quieting method works better than the alternatives and is saving lives.
In the study, the researchers observed more than 1,000 patients that received the desensitizing procedure along with incompatible transplants. The researchers matched them to an equal number of patients who stayed on the waiting list without receiving a transplant (receiving only dialysis), and those who eventually did receive a compatible transplant.
Every year, the patients who received the incompatible transplant had a significantly higher likelihood of survival. After eight years, about 77 percent of those who had received the incompatible transplant were still alive, compared to 44 percent of those patients who were still on the waiting list. And though desensitization is expensive, so is dialysis, the study authors argue.
“For the first time, we have definitively shown that incompatible live donor kidney transplantation provides almost twice the survival of a patient’s next best option,” Dorry Segev, a professor of surgery at Johns Hopkins and the lead author of the paper, said in a press release. “This is great news for patients who have healthy, willing live donors but who have been relegated to the waiting list because of HLA [antigen] incompatibilities. Through this study, we now know that those donors can donate today, those transplants can happen and those lives can be saved.”
That’s heartening news for patients currently waiting for a kidney transplant, especially since exciting sounding bioengineering schemes designed to increase the number of organs available to recipients aren’t yet being implemented. If more hospitals transplant incompatible organs (after using the desensitization technique), they could save thousands of lives per year.
The same technique could be used for recipients of other types of organ transplants, too.
source: popsci.com By Alexandra Ossola