The T cell is one of two main classes of lymphocytes (a type of white blood cell), which play a role in the body’s immune system. Scientists have long believed that 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.
Fady Baddoura, M.D., 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. "Future studies will use this method to further analyze how memory T cells act against transplanted tissue, and identify new compounds that may block this rejection function."
The research team believes 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 Fadi Lakkis, M.D., of Yale University.
"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.
VA research such as the T-cell study provides improved medical care for veterans, as well as the population in general. Through its unique affiliation with medical schools, VA plays a crucial role in educating future physicians in research and clinically oriented areas.
VA has integrated more than 900 medical centers, clinics, nursing homes and other operating units into 23 health care networks. These Veterans Integrated Service Networks, or VISNs, pool and align resources like medical research to increase efficiencies and provide optimal patient care.
SPECIAL NOTE: Dr. Baddoura is available to discuss the T Cell Organ Transplant Study. For interviews, please contact Arlene Kelly, Public Affairs Office, Buffalo VA Medical Center, at (716) 862-8751 or arlene.kelly@med.va.gov.
For Information Contact:
Arlene Kelly
(716) 862-8751
arlene.kelly@med.va.gov
Journal
Proceedings of the National Academy of Sciences