T-Cells Prevent Rejection of Transplanted Pancreatic Islet Cells

A recent article by diabetes researchers described a new method for enriching the population of regulatory T-cells that are able to prevent transplanted pancreatic islet cells from being rejected by the host's immune response.
Islet cell transplantation is a treatment option for type 1 diabetes, which is an autoimmune disease unrelated to external factors such as obesity. However, to prevent destruction of the transplanted cells, patients must be placed on lifelong immunosuppressive therapy. The drugs required have powerful side effects and may be toxic to islet cells as well.
In the current study, investigators at Cornell University (Ithaca, NY, USA) worked with a mouse model of human type 1 diabetes. Dendritic cells taken from nonobese diabetic (NOD) mice expressing the CD4+ surface protein were stimulated to express the CD25+ surface protein as well. This population of immune cells was then given to another group of NOD mice that had also received a transplant of normal pancreatic islet cells.
Results published in the February 20, 2007, issue of the Proceedings of the [U.S.] National Academy of Sciences revealed that the transplanted islet cells prevented diabetes, and the transplanted immune cells prevent rejection of the graft.
"If we can replicate this in humans, we might someday do away with the lifelong use of powerful immunosuppressive drugs that patients must take after islet cell transplant--drugs that we believe also do harm to islet cells over time,” explained senior author Dr. Manikkam Suthanthiran, professor nephrology and transplantation medicine at Cornell University. "We also determined that this approach shields the pancreas' own islet cells from harm. That is important, because newly diagnosed type 1 diabetes patients often have some percentage of working islet cells remaining. This strategy might protect those cells, as well as the transplanted cells.”


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