Now, a blood test to detect organ transplant rejection

A simple blood test can now help doctors in identifying the clues of transplant rejection — a feat that could pave the way for a non-invasive alternative for diagnosing organ rejection before damage occurs, says a new study.

Usually, in case organ function drops, a small piece of tissue will be removed and checked for rejection.

But many times, the organ may already be damaged by the time doctors spot a problem.

A simple blood test for the proteins involved in the inflammatory response of rejection could provide the answer, said Atul Butte, co-senior author of the new research and an associate professor of medical informatics and of paediatrics at the Stanford University School of Medicine.

The technique could help 40% of heart transplant recipients who experience an acute episode of rejection in their first year after transplantation.

To identify the protein markers involved in organ rejection, Butte and his team used a publicly available repository that documented changes in mRNA (messanger-RNA) levels, " the molecules that instruct cells to make proteins," during organ rejection.

These changes gave the team clues about which proteins appear in the blood during rejection.

From 45 protein candidates, the team zeroed in on 10 that could be identified by tests already used in a clinical setting.

Using blood samples from 39 kidney and 63 heart transplant patients, they found three proteins which reliably increased during an acute rejection.

"The test could be used to adjust the levels of immuno-suppressant drugs administered, increasing them only if rejection is imminent, thus minimising the side-effects," said Minnie Sarval, co-author of the study.

"It could also potentially prompt doctors to conduct a biopsy [only] if necessary rather than biopsying straight away," New Scientist quoted her as saying.

More research will show whether these diagnostic markers can predict an acute episode of rejection before any change in organ function is witnessed.

"Identifying a protein marker that is elevated in the blood before rejection could represent a significant advance which could enable early intervention with treatment," said Steven Sacks at the centre for transplantation at King's College, London.

"Their next challenge would be to examine whether patients treated on the basis of this test do better than those who do not have the benefit of such testing and who have to wait until organ damage occurs before immuno-suppressant treatment is increased," he said.

The team is now planning clinical trials with a hope that their test will be available within three to five years.