Using the new imaging process, the authors were able to clearly see that the ratio of protective T cells to destructive T cells differed markedly in the transplant tolerant mice compared with the mice in which transplant tissue was rejected. Among the "rejection mice," red cells rushed into the transplant far in advance of infiltration into the transplant by the tolerance hosts.

"As the events of rejection proceeded, the number of transplanted infiltrating T cells vastly exceeded those present in the tolerant transplants, even though the numbers of 'protective' yellow and green cells were equal in these groups at a later point in time," explains Koulmanda. "This is the first time that we have been able to monitor transplanted allograft tissue in a live lab animal. While static images of cells have been captured in the past, our new method captures much more than just random snapshots of the process."

"A picture really is worth a thousand words," adds Strom. "By enabling us to visualize this process, this new system has given us a clearer understanding of both quantitative and qualitative characteristics of the CD4 T cell response to allografts in rejecting and tolerized hosts. Fourteen days post-transplant, we were able to witness as costimulation blockade-based therapy inhibited infiltration by [the fluorescent red] Teff cells. Given the effectiveness of these tools, we hope to construct a road map such that we can create drug-free transplant tolerance for our patients in the future."

Source: Beth Israel Deaconess Medical Center