The protein signals are now being validated in liver and lung transplant recipients as well. Currently, all organ recipients receive functional monitoring of their new body parts. The Maurice team found three easily measured proteins that rise in the blood during acute rejection, in which a patient's immune system attacks his or her transplanted organ.

If organ function drops, doctors cut a tiny sample from the transplanted tissue to check for rejection, and then adjust patients' immune. A simple, inexpensive blood test could soon help doctors halt organ rejection before it impairs transplanted hearts and kidneys. The new blood test circumvents the invasive, expensive, slow system now used to keep tabs on transplants. Heart transplant patients get regular echocardiograms, for instance. "In the past, we couldn't spot rejection episodes until they harmed the organ," said Atul Butte, MD, PhD, who is co senior "Our goal is to develop blood tests that will keep transplanted organs functioning so that patients can avoid a second transplant." Butte and his collaborators have made a big step toward that goal.

The research, which will be published online in PLoS Computational Biology, is the first ever report of an immune rejection signal that is shared by two kinds of transplanted organs.