20 May 2011

Transplantation without immunosuppressants and without organ rejection

Immunity has been weaned from attacking a donor organAlla Solodova, Infox.ru

Scientists are a few steps closer to the dream of transplantology. They canceled the rejection of the donor organ. It is possible that soon patients with transplanted organs will live without immunosuppressants – drugs that depress the immune system.

Researchers from King's College London prevented the rejection of the transplant by the immune cells of the recipient animal. At the same time, the immune system has not lost its ability to fight infection and degenerated (atypical, cancerous) cells.

Regulatory T cells are a special population of lymphocytes that does not participate in hostilities, but maintains peace and harmony between the cells of the immune system and the whole body. They "give orders" to other immune cells and "incite" them against enemies. Or, on the contrary, they pacify, allowing the native organs not to quarrel with each other. That is, it is the regulatory T-cells (T-reg) that determine the body's response to the appearance of an infection, tumor, or someone else's graft tissue.

For a long time, immunologists did not believe that there are cells in the body that suppress excessive activity of the immune system. However, this is true: without regulatory T cells, autoimmune diseases and spontaneous inflammation begin.

T-reg cells resist re-infection with pathogenic microbes, protect beneficial intestinal bacteria and contribute to the normal course of pregnancy. But they also help cancer cells hide from immunity.

Scientists hope that by taming regulatory T cells, they will be able to make the immune system more aggressive towards cancer, cure patients of autoimmune diseases and prevent organ rejection after transplantation. These ideas have been developed for years and are being tested in laboratories and hospital wards.

This time encouraging results appeared at once from three independent international groups of researchers.

Pervinder Sagoo's group created T-reg cells with the graft antigen present on their surface. To do this, scientists cultivated healthy immune cells of the recipient animal with donor tissues and in this way taught them not to attack strangers. They multiplied the "trained" cells. Next, biologists transplanted a piece of human tissue into laboratory animals and injected "trained" lymphocytes. As a result, they perceived someone else's tissue as their own and "taught" the entire immune system to do this. The recipient mouse accepted the donor tissue, and at the same time the immune system did not lose the ability to attack truly dangerous cells and bacteria. If T-reg had not taught the immune system not to reject the donor organ, then it (immunity) would have to be suppressed with special immunosuppressive drugs. In this case, immunity loses not only the "anti-donor", but also the rest of the protective functions.

In two other papers, the groups of Andrew Bushell and Bruce Blazer described molecular mechanisms that can be used to increase the rate of reproduction of regulatory T cells.

Scientists of independent laboratories are unanimous that the proposed and tested methods of immunotherapy (in particular, those thanks to which the mouse immunity did not "get angry" with human tissue) should replace immunosuppressive drugs. After all, by suppressing the immune system, doctors force the immune system to ignore the real danger – infections and cancer cells. Therefore, the recipient lives with a new organ and a bouquet of diseases that would not occur in an organism with full immunity.

The results of all studies can be found in the latest issue of the journal Science Translational Medicine (Sagoo et al., Human Regulatory T Cells with Alloantigen Specificity Are More Potential Inhibitors of Alloimmune Skin Graft Damage than Polyclonal Regulatory T Cells – VM).

Portal "Eternal youth" http://vechnayamolodost.ru20.05.2011

Found a typo? Select it and press ctrl + enter Print version