Marrow Donors Don’t Need Perfect Match, Study Finds

Medical researchers unveiled new evidence Wednesday showing that doctors don’t need a perfect match when they try to transplant bone marrow into someone whose blood-producing cells have been damaged by leukemia or another deadly illness.

Bone marrow transplants are usually most successful when the marrow is donated by a brother or sister whose cells have the same pattern of surface proteins. When the protein pattern matches, it reduces the likelihood that the donated marrow will be rejected or produce serious side effects.

But researchers at the Medical College of Wisconsin, using special techniques to cleanse the donated marrow, found that transplants can be successful when the protein pattern in the donor’s marrow is similar to, but not identical to, the recipient’s.

The findings, reported in the current New England Journal of Medicine, suggest that “we can now start tapping into the enlarging pool of volunteer marrow donors” whose marrow “will lead to satisfactory results for many patients,” said Dr. Robert C. Ash, chief author of the study.

The ability to use marrow from unrelated donors is important because only about 30% of patients who might benefit from a bone marrow transplant will have a brother or sister whose marrow is perfectly matched, Ash said.

This issue was dramatized last week when a 43-year-old Walnut woman disclosed that she was having a baby in the hope that the newborn can become a bone marrow donor for her 17-year-old daughter, who has leukemia. Tests have shown that the fetus’s bone marrow is nearly identical. The birth is expected in April.

In the four-year study of 55 patients, the transplants were successful in 48% of patientswith early leukemia, 32% of the volunteers whose leukemia had reached an advanced stage, and 63% of the patients who suffered from diseases other than leukemia.

In all, 31 of the 55 patients died, usually from infection.

Graft-versus-host disease, a potentially deadly reaction that appears when the cells of the transplanted marrow attack the body, occurred in nearly half the patients. Ash and his colleagues characterized that rate as relatively low.

To reduce the risk of graftversus-host disease, the donated marrow was initially treatedwith chemicals to kill white blood cells that trigger an immune response.