New test quickly detects kidney transplant rejection

SYDNEY - A urine test devised by researchers is faster, simpler and less invasive than current biopsy tests to detect kidney transplant rejections.

The first ever urine test to detect such rejections has been developed by University of Otago researchers, based on a seven-year study of New Zealand, Australian and Swiss kidney transplant patients.

This accurate test could replace the current test, an invasive biopsy procedure, says study coordinator Alex McLellan, from Otago University’s microbiology and immunology department.

Although the idea was first tested in 2002, proof that the test could be used to monitor the effectiveness of renal transplants required years of patient sample collection and research into a molecule present in the urine.

The main challenge facing transplant physicians is the host’s immune system, which sees the graft as foreign and attacks the transplanted organ,” says McLellan.

Keeping the transplanted organ alive and functioning in the host requires potent immunosuppressive drugs, which must be taken for the person’s life, adds McLellan.

Detecting transplant rejection at the earliest possible time is essential to prevent transplant loss because it allows immediate intervention with additional immunosuppressive drugs.

The newly developed urine test detects one of the molecules (called Major Histocompatibility Complex or MHC molecules) that are released from the kidneys into urine during transplant rejection.

In the study, the urine levels of MHC molecules soared during transplant rejection, and could be detected days before confirmation of rejection using the standard biopsy method.

They found that these patients who tested positive for MHC in urine had a greater than 90 percent chance of suffering transplant rejection.

The kidney biopsy is still the most reliable method to date for diagnosing transplant rejection but is invasive,” says McLellan.

“The (latest) urine test is rapid, simple and non-invasive, requiring basic materials to detect a molecule released into urine during transplant rejection, McLellan says.

McLellan hopes the test, which is unlikely to become available for some years until further testing on larger groups of kidney transplant patients has been done, will improve diagnostic monitoring during the post-transplant hospitalisation of patients.

These findings were published in Transplantation.