"Bone marrow is the seat of the immune system, the body mechanism that fights what it perceives as foreign," explains TIME medical columnist Christine Gorman. "The new treatment teaches the transplanted immune system to recognize the recipient as self and not go on the warpath against the recipient." The new process, which makes use of a substance called CTLA4-Ig, involves mixing selected cells from the recipient with the bone marrow of the donor before transplantation. The process essentially gives the bone marrow "an introduction" to its new self, says Gorman. However, while the promise is great, the treatment, which was tested on 12 young victims of advanced leukemia, is not completely effective and will require further research. "It’s a step toward allowing doctors to more finely manipulate the immune system in transplantation," says Gorman. Researchers believe the process could also have applications for heart, kidney and other organ transplants.
Of all the transplants made possible by modern medicine, bone marrow transfers have been among the most treacherous because of the necessity of closely matching donor and recipient. But a new treatment, reported in Thursday’s New England Journal of Medicine, indicates that such transplants may one day be possible between poorly matched donors and recipients -- a possibility that could significantly increase the chances of obtaining the life-saving transplants for leukemia and other cancer patients.