I) Transplantation Tolerance

 Hans J. sclitt and colleagues in Hanorver, Germany, in a study based on heart transplant in rats, reported that the induction of transplant tolerance depends on the small number of blood cells that are passed from donor to recipient during the transplant. In the first two weeks after a transplant. When the blood cells were removed it was found that the animals rejected the transplanted organ. This was published in the November 1, 1999 issue of Nature Medicine (1999, 5:1292-1297).

Addressing the same issue, Herman Waldmann in a review article in Nature Medicine (1995; 5:1292-1245-1248) said that establishing tolerance induction was a feasible alternative to immunosuppression after organ transplant. He felt that it could be achieved through cooperation between basic and clinical researchers Regulatory and industry.  Even though there were a number of stumbling blocks.

II) IMMUNOSUPPRESSION BYPASSED IN A KIDNEY TRANSPLANT RECIPIENT

A report that appeared in the August 1999 issue of Transplantation stated that physicians at Massachusetts General Hospital have induced a state of immune tolerance in a kidney recipient that has allowed the patient to forego immunosuppressive drugs without her body’s rejecting the kidney.

The patient had developed kidney failure as a result of multiple myeloma. The immune state was made possible because the woman also received a bone marrow transplant at the time of her kidney operation in September 1998. The kidney and bone marrow were both donated by the woman’s sister.

The multiple myeloma had made her unable to tolerate a standard bone marrow transplant that would destroy her own marrow by chemotherapy or radiation. The doctors, therefore, used a new, less toxic preparation for bone marrow transplants that was developed by the Massachusetts General Hospital Transplantation Biology Research Centre along with Bio Transplant incorporated. According to them, this approach allowed the patient to accept the donor marrow but preserved most of his or her own marrow, leading to the blended immune system that characterized mixed chimerism. The patient received cyclosporine for 73 days after the transplants, and she received two post-transplant infusions of donor white blood cells. The recipient’s myeloma was no longer at a detectable level and donor cells could no longer be found in her bone marrow.

“This kind of transient chimerism had been observed in the pre clinical studies we have performed in monkeys, and we need to understand better the mechanism behind this phenomenon.” said David Sachs MD, one of the authors of the study.