Researchers identify immune cells that contribute to transpl
Non-circulating memory T cells, whose main function is to provide local protection against re-infection, contribute to chronic transplant rejection, researchers reveal in a paper published today in Science Immunology. The scientists show that these "tissue-resident memory T cells" are harmful in situations where antigens that the cells recognize are present in the body for a long time, such as in cases of an organ or tissue transplant.

Immunologists and transplant surgeons have long been aware that T cells—a subset of immune cells central to the development of acquired immunity—play a critical role in the acute rejection of a transplanted organ. But until now, the role of resident memory T cells in transplant rejection was overlooked.

Using a mouse model of kidney transplantation, the researchers showed that, over time, activated T cells that infiltrate a transplanted organ morph into resident memory T cells. They discovered that if they surgically conjoin blood circulation of two mice, both of which received identical kidney transplants, memory T cells formed in transplanted organs don't travel from one mouse to the other. Similarly, if a transplanted kidney was then removed and re-transplanted again to yet another mouse, resident memory T cells stayed in the transplanted kidney and didn't disseminate anywhere else in the recipient's body, establishing that these cells reside in the tissue permanently.

"There is an assumption that T cells in transplanted organs or tissues are exhausted and dysfunctional and may not contribute significantly to tissue rejection," said the investigator. "Our work shows that tissue-resident memory T cells are functional and destructive."

Specifically targeting these cells could improve clinical transplant outcomes while preserving the immune system's ability to fight off infections, reducing the side effects of current systemic immunosuppressive therapies.

Science Immunology
Source: … 6/sciimmunol.abc8122