Posted by Brigham and Women's Hospital February 5, 2014
Physicians and researchers commonly have believed that the key to ensuring the long-term success of a face transplant is to prevent the recipient’s T cells (immune cells) from attacking T cells in the donated tissue. Recent Brigham and Women’s Hospital (BWH) research, however, has shown that donor T cells transferred as part of the face transplant may attack recipient T cells and, thus, also contribute significantly to rejection episodes – not just the other way around.
The BWH Restorative Surgery team, led by Dr. Bohdan Pomahac, has had great success in pioneering face transplantation, but they also acknowledge that there is much to learn. Determining how a recipient accepts or rejects a donated face and how to address rejection episodes are considered to be among their most important challenges.
Following a face transplant, or any type of human organ/tissue transplant, T cells from the recipient mount an immune response to the donated tissue, threatening its survival. Thus far, rejection episodes following face transplants at BWH have been controlled successfully through immunosuppression medication, enabling all our recipients to maintain acceptance of their transplanted face.
To gain a deeper understanding of what takes place during these rejection episodes, a team of researchers led by Dr. George F. Murphy, Director of the BWH Dermatopathology Program, examined 131 face transplant biopsies (tissue samples) from five patients who received a face transplant at BWH between 2009 and 2013. Along with analyzing the samples to determine rejection levels and to guide anti-rejection therapy, researchers added biomarkers to enable them to distinguish between donor and recipient cells while examining them under a microscope. They subsequently found that during active episodes, many and often most of the immune cells involved in rejection were of donor origin.
“The conventional belief about face transplant was that rejection is directly related to the recipient T cells attacking the donor T cells of the face, which are perceived as foreign to the recipient’s immune system,” explains Dr. Christine Lian, a skin pathologist at BWH and lead author of this study. “We now need to rethink this process. Based on our findings, it is clear that the donor T cells, which are transferred as part of the new face, potentially play a significant role in the rejection process as well, with the intriguing possibility that they serve to defend the face against the recipient immune attack.”
Now, as researchers and physicians explore the development of improved immunotherapy strategies, they are bound take greater heed of what the donor’s immune cells are doing following a face transplant. Not only that, these new findings also are likely to spur research into whether similar donor-recipient interactions are taking place in other types of transplantation.
These findings were published in the January 17, 2014, edition of Modern Pathology.
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