Transplantation of organs is typically thought to be a lifelong cure to serious diseases. Unfortunately, the survival rate of transplanted organs is around 50% after 5-10 years, primarily due to chronic rejection. Short term survival rates have drastically increased over the past 20 years, however long term survival has remained unchanged over the same time period. The cause and successful treatment methods of chronic rejection are still unknown, although recently identified cell types may hold the key.

Transplantation of an organ also involves the transfer of immune cells from the donor to the recipient. Recently, certain types of white blood cells have been discovered to live within organs, with their primary purpose being the prevention of infection. We asked the questions; what happens to these cells after transplantation to the recipient? Can immune cells from the recipient also take up residence in the transplanted organ? Do either or both of these cells influence the rejection of the organ?

We have found that liver transplants in mice do indeed involve the transfer of immune cells. In experiments replicating transplantation between identical twins in humans, most of these cells remain within the liver, however some also travel to other organs within a week of being transplanted. In transplants replicating unrelated donors and recipients, donor cells were killed by the recipient’s immune system, also within 1 week. We’ve also found that recipient immune cells establish themselves as resident within the transplanted organ. We are currently working on relating these results to our understanding of the cause of chronic rejection of organ transplants.