Scientists find clues to kidney transplant success

European scientists have found a full range of markers in the blood of kidney transplant patients which could predict whether their new organ will be a success and whether they need large amounts of medication to help it.

The researchers said on Tuesday the finding may help doctors to give more personalized care to transplant patients and to modify the amount of powerful immunosuppressant drugs they have to take to prevent their bodies from rejecting a new kidney.

The scientists, led by Maria Hernandez-Fuentes at King's College London, studied various groups of kidney transplant patients in Europe, including 11 patients who had stopped taking their drugs after the transplant but did not reject the donor organ since they appeared to have a natural "tolerance" for it.

They carried out detailed tests of blood samples and found differences in the immune systems particular to these patients.

"We hope that now we can start to look at screening other patients to see if they also have similar markers in their blood," said Rachel Hilton, a renal consultant at Guy's Hospital in London and co-author of the study.

"There may be many more patients out there who potentially could reduce or stop their medication if we can screen them to see if their immune system looks similar," she said in a telephone interview.

Kidney transplants are the most common type of major organ transplant worldwide - around 1,550 are carried out in Britain and around 18,000 in the United States every year. The average lifespan of a transplanted kidney is 12 years, rising to around 20 years in some cases if the kidney is from a living donor.

For many patients, a kidney transplant opens up a new life, but it also means they must take powerful immunosuppressant drugs - which have a wide-range of side effects - for the rest of their lives to make sure the new organ is not rejected.

"If you're on these transplant drugs for life, then you have the side effects for life as well as the benefits," said Hilton.

"The main side effects are increased risk of infection and a higher risk of future cancers, so they are very undesirable side effects in both the short- and the long-term."

The European team compared the 11 patients who had a natural tolerance of the new kidney against patients who were taking varying amounts of immunosuppressants, as well as patients who were taking the drugs but also showing signs of rejecting the donor organ, and a group of healthy volunteers.

They described what they found what as a "full set" of markers which made "tolerance fingerprint" in some patients.

The findings were later corroborated in another study by the Immune Tolerance Network in the United States and both studies were published by the Journal of Clinical Investigation.