A new blood freezing technique has enabled a U.K. woman to donate an "incompatible" kidney to her sister, saving her from probable death, Sky News reported.
Maxine Bath's blood pressure was so low because of years of kidney failure that parts of her body were being starved of oxygen.
Her eyes had already been damaged and doctors feared her brain could be next.
Only a transplant could save her, but her antibodies would have destroyed a new organ.
For the first time, doctors at University Hospital in Coventry used a freezing technique to filter out the antibodies from her blood, allowing her sister, Michelle Titmus, to donate one of her kidneys.
"In a year's time I could have been blind or dead if I hadn't had the transplant," Bath told Sky News. "Now I'll be able to lead a normal life, eat what I want, and go out and not worry about going to hospital for dialysis. It's changed my life altogether."
Existing techniques remove antibodies from the blood using a filter with microscopic holes. But that would have reduced Bath's blood pressure still further, with possible lethal results.
So the doctors separated the watery plasma that contains all the antibodies from her blood.
They then pumped the plasma through a long tube which was surrounded by icy water.
This caused the antibodies to clump together, so they could be trapped by a filter with much larger holes, allowing the rest of the plasma through unhindered.
"The antibodies came out and her blood pressure barely changed," Dr. Rob Higgins explained. "She tolerated the treatment very well and was able to go to the operating theater without any huge drama."
Around 10 to 20 patients a year in Britain could now have a transplant they would not otherwise be able to have.