Medical practitioners are a step closer to improving treatment of people who need organ transplants, with new research from The University of Western Australia providing important insights into how immune cells respond to transplants.

Organ transplants are the final treatment option for many patients with end-stage diseases. However, despite improvements in the short-term, long-term survival rates of patients is low. This is primarily due to chronic rejection, caused by a long-term, uncontrollable immune response against the transplanted organ.

Clinical Professor Michaela Lucas from the UWA Medical School, senior author of the study published today in Cell Reports, said the immune system, which normally keeps us safe from infection, becomes harmful after transplantation as it recognises the transplanted organ as a foreign object.

“Drugs are used to suppress this response, but current treatments are not effective at protecting transplanted organs in the long-term.”

Professor Michaela Lucas

“New approaches to immune-suppressive drug treatments are needed to improve outcomes for transplant patients.”

Professor Lucas said the specific ways in which immune cells interacted with transplanted organs in the body had not been well understood until now, and this understanding was important to improve treatments and the health of organ transplant patients.

Amy Prosser, research fellow from UWA’s Medical School and first author of the study, said the study looked at how immune cells from the organ donor and recipient patient responded to liver and heart transplants, where these cells went, and how the organs changed after they were transplanted.

“We found that there are two types of immune cells which originate from the donor in transplanted organs – those that remain in the organ itself, and those that enter the recipient’s bloodstream and travel to other parts of the body,” she said.

“In transplants where the donor and recipient are genetically identical, donor immune cells live for a long time, but when there are genetic differences, the recipient’s immune system kills the donor organ cells. These donor cells are important for protecting the organ from infection and making sure it functions normally, so their loss could have a major impact on transplant outcome.”

“In both genetically identical and non-identical transplants, the recipient’s immune cells enter the transplanted organ and change its biology, leaving it more vulnerable to infection and cancer, and unable to heal normally. Over time this can cause serious health issues for transplant patients”.

The scientists hope that insights into the immune response during organ transplantation will lead to the development of more effective and targeted drugs that protect the transplanted organ’s immune cells.