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Press Release
Study Yields Clues on Body's Rejection of Transplanted Organs - Findings May Enable New Anti-Rejection Methods
Release 5 p.m. ET Monday, April 29, 2002
Using a new method to track immune-cell activity in mice, researchers from the Department of Veterans Affairs (VA) and Yale and Emory universities showed for the first time that certain white blood cells may trigger the body's rejection of transplanted organs even without help from the spleen and lymph nodes. The findings, published in the April 30 Proceedings of the National Academy of Sciences USA (PNAS), may lead to the development of new drugs to prevent organ rejection.
Scientists have long believed that immune, or white blood, cells called T cells rely on the spleen and lymph nodes to mount an immune response against toxins, bacteria and the foreign blood cells of a transplant. In the new study, investigators discovered that memory T cells, unlike naïve (resting) T cells, can trigger the rejection of a transplant even when the spleen and lymph nodes are removed.
Researcher Dr. Fady Baddoura of the Buffalo VA Medical Center developed a new method for staining and visually tracking memory T cells to follow their actions in the tissue of transplanted hearts in mice. The mice used in the study had their spleen and lymph nodes removed, thus disabling other types of T cells, such as killer T cells. But the animals' memory T cells were still able to react and reproduce on their own, mounting an attack against the transplanted hearts.
The tissue staining method "provides reliable visual proof of the presence, location and intensity of the T cells responsible for rejection," said Dr. Baddoura.
He said future studies will use the tissue-staining method to further analyze how memory T cells act against transplanted tissue, and to identify new compounds that may block this rejection function.
Researcher Dr. Fadi Lakkis from Yale University said the findings may help improve the success rate of organ transplants in the future. "Despite improvement in short-term outcomes, most transplanted organs fail over time," said Dr. Lakkis. "Poor long-term outcomes are in part due to the presence of memory T cells that are still active despite the administration of anti-rejection drugs. Therefore, this study alerts clinicians to the importance of memory T cells and underscores the need to develop new medications that block memory T-cell function after transplantation."
This study was funded by grants from The National Institute of Health and VA Merit Review.
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