Before the transplants, both donors and recipients were given skin tests to gauge their reaction to 17 common allergens, such as house dust, cat hair, penicillin, ragweed and other substances. They were then given the same allergy tests 30 days, 100 days and finally more than a year after the transplant.

In some cases, initial tests showed that a donor was allergic to a substance but the recipient of that person's marrow was not. But the later tests indicated that the recipients developed some of the same allergic reactions after the transplants.

The research, by scientists from the University of Washington and the Fred Hutchinson Cancer Research Center, is reported in the current New England Journal of Medicine.

Allergies are abnormal immune system reactions to ordinarily harmless substances. Many immune system cells are produced in the bone marrow. The researchers did not discuss whether other aspects of immunity are passed along.

They said they believed the allergic reactions in the recipients did not result simply because the transplanted bone marrow contained a kind of immunoglobulin, which functions as an antibody and is active in allergies. Rather, they said, the recipients appeared to have adopted the donor's immune system cells that produce the immunoglobulin.