Scientists at Stanford University in California have developed a way to transplant kidneys without being repelled by the recipient's organism. Usually, the immune system is looking for foreign cells, which it then attacks - unless the immune system is strongly suppressed with drugs. In the new method of Samuel Strober's researchers, the patient also receives short-term medication after the operation, but is subsequently irradiated in small doses. At the same time, the physicians administer a preparation that reduces those cells that are susceptible to attack by the immune system. The recipient is then injected with blood stem cells from the donor. These stem cells form new blood and immune cells in the bone marrow that mix with the patient's immune cells. Strober: "In this way it comes to no rejection of the donor organ." The advantages of the new method are obvious: It is no longer necessary to take drugs for life and also the donor must be no longer related to the recipient. The treatment has already been performed on four patients, two of them no longer need medication.