Physicians at Massachusetts General Hospital have reported that they 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 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 findings were reported on August 27 in Transplantation.
The patient had developed kidney failure as a result of multiple myeloma. Although the cancer made her unable to tolerate a standard bone marrow transplant that would destroy her own marrow by chemotherapy or radiation, the doctors used a new, less toxic preparation for bone marrow transplants that was developed by the Massachusetts General Hospital Transplantation Biology Research Center.
"This approach allows the patient to accept the donor marrow but preserves most of his or her own marrow, leading to the blended immune system that characterizes mixed chimerism," said a statement from BioTransplant Incorporated (www.biotransplant.com), which collaborated with the Boston team. The patient received cyclosporine for 73 days after the transplants, and she received two post-transplant infusions of donor white blood cells. Her myeloma "remains at a nearly undetectable level at this time," BioTransplant said on August 24. In addition, donor cells can no longer be found in the recipient's bone marrow.
"This kind of transient chimerism had been observed in the preclinical studies we have performed in monkeys, and we need to understand better the mechanisms behind this phenomenon," said David Sachs, MD, one of the authors of the study.
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