A KIDNEY transplant may save your life, but it comes at a cost: the immunosuppressant drugs taken to stop your body rejecting the organ can leave you more vulnerable to infections and boost your risk of cancer. But there may soon be a way to identify patients whose bodies have accepted their transplants, meaning they could reduce their drug intake, or stop altogether.
鈥淎t the moment immunosuppressants are very much drugs for life,鈥� says Robert Lechler of Kings College London. He estimates that the immune systems of up to one-fifth of kidney-transplant recipients may eventually learn to tolerate their new organ. However, as such tolerance has been almost impossible to identify, the vast majority stay on drugs as a precaution. 鈥淐oming off the drugs is very risky because as soon as rejection starts, you damage the kidney,鈥� says Lechler.
To find a better way of identifying organ-tolerant patients, Lechler and colleagues analysed blood samples from 83 kidney-transplant patients 鈥� 11 of whom had stopped taking their immunosuppressants, against their doctors鈥� advice, yet suffered no organ rejection 鈥� plus 17 healthy individuals. They examined the patterns of gene expression for 1467 genes involved in immune system function and also the relative proportions of immune cells in the blood samples. From this, they identified an 鈥渋mmune fingerprint鈥� for the tolerant state that could identify patients whose body appeared to have accepted their donated kidney.
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Lechler believes the test can identify immune-tolerant patients with 82 per cent accuracy and hopes that it could eventually be used to decide which patients could benefit from the gradual withdrawal of their drugs. The results were presented at the International Conference on New Trends in Immunosuppression and Immunotherapy in Berlin, Germany, last week.
鈥淭he test could help decide which patients could benefit from the gradual withdrawal of their immunosuppressant drugs鈥�
At the same meeting, a separate group led by Vicki Seyfert-Margolis of the Immune Tolerance Network in Bethesda, Maryland, reported the results of a similar analysis on 22 kidney-transplant patients whose immune systems had grown tolerant of their new organ. While some markers were the same as those identified by Lechler鈥檚 group, there were also some differences. Joining forces, the groups hope to produce a workable test within two years.
鈥淲hat these two teams have discovered are some very interesting 鈥榮ignatures of tolerance鈥�,鈥� says Laurence Turka, an immunologist at the University of Pennsylvania in Philadelphia. 鈥淭he next challenge is to find a new group of [immune-tolerant] patients in which you can validate these signatures.鈥�
The goal is to get all tolerant transplant-recipients off drugs, although 鈥渆ven getting to the point where you鈥檙e minimising the use of these drugs would be a significant achievement鈥�, says Seyfert-Margolis.
