Science News Examiner: New discovery may end transplant rejection

Science News Examiner: New discovery may end transplant rejection: "Professor Jonathan Sprent and Dr Kylie Webster from Sydney's Garvan Institute of Medical Research focused on a different type of T cells – known as regulatory T cells (Treg) – in this study. Tregs are capable of quieting the immune system, stopping the killer T cells from seeking out and attacking foreign objects. Usually, these cells live in basic equilibrium, allowing the killer T cells to destroy what needs to be destroyed, but stopping them once the infection is over. The idea was to boost the number of Tregs in the system, quieting the killer T cells for a period of time sufficient for the body to accept the new tissue. After that point, the immune system would return to normal activity.

Using a complex that contained a molecule known as interleukin-2, a molecule that promotes T cell proliferation, the researchers radically increased the number of Tregs in healthy mice before performing the transplants, effectively quieting the killer T cells. Webster explained what followed after the transplant: 'The numbers of T regulatory cells dropped over time, and the immune systems returned to normal in about two weeks. By that time 80% of the mice had accepted the grafts of insulin producing cells as their own. This acceptance rate is very high for transplantation, with mice normally rejecting grafts within 2-3 weeks. A graft is considered accepted if it's tolerated after 100 days. We took some mice out to 200-300 days, and not one of them rejected.' [EurekAlert]"