There are more patients waiting for new kidneys than any other organ. Of the six organs that can be donated to someone in need, kidneys are both the most in demand and the most offered up. Still, many patients die before they ever find a matching donor. However, according to a new study published this week in the New England Journal of Medicine, a revolutionary procedure known as desensitization makes organ donations between unmatched pairs now a medical possibility. The researchers discovered that by manipulating a kidney transplant recipient’s immune system, they can prevent it from rejecting an organ from a donor with mismatched human leukocyte antigens.

When doctors seek a good match for an organ transplant, a critical factor they look for is whether the donor and recipient have compatible human leukocyte antigens (HLA). These are a type of protein found in most cells in our body that are unique to each individual. HLAs are not harmful within our own bodies, but because they can cause an adverse reaction in someone with different antigens, our bodies create antibodies to protect against unmatching, or foreign, HLAs. During an organ transplant, if a patient receives an organ from a donor with an unmatching HLA, the body will view the organ as foreign and reject it. However, with desensitization, doctors manipulate the patient's immune system so that it will not reject an organ with mismatching HLA.

For the recent study, funded by the National Institute of Diabetes and Digestive and Kidney Diseases, a team of researchers looked at the overall survival rates of 1,025 patients from 22 different medical centers who had received kidney transplants from HLA-incompatible live donors. They then compared these patient’s survival rates with the survival rates of patients who remained on the organ waiting list and those who received kidneys from deceased donors at one-, three-, five-, and eight-year intervals.

Desensitization involves first taking the antibodies out of a patient’s blood and then infusing them with new antibodies while their body regenerates the removed antibodies. According to The New York Times, the new antibodies that the body generates are less likely to attack an incompatible organ, although it's not yet clear why this is. All together, the desensitization process can take up to two weeks. Patients whose new antibodies look as though they still may compromise their new organ are given medication that destroys any white blood cells that are of risk to the new kidney.

According to the results, “patients who received kidney transplants from HLA-incompatible live donors had a substantial survival benefit as compared with patients who did not undergo transplantation and those who waited for transplants from deceased donors,” the authors wrote.

Even better, desensitization is not restricted to kidney transplants, and could be used in other living donor transplants. However, the procedure is not without its setbacks and can cost upwards of $30,000 on top of the regular transplant operation costs, which run about $100,000. Despite the costs, the procedure may be worthwhile as it saves patients from a lifetime of dialysis — a treatment that helps to remove excess wastes in the body when the kidneys fail. The treatment can cost upwards of $70,000 a year and is very time consuming.

Source: Orandi BJ, Luo X, Massie AB, et al. Survival Benefit with Kidney Transplants from HLA-Incompatible Live Donors. The New England Journal of Medicine . 2016