Results will be presented at the International Society for Heart and Lung Transplantation (ISHLT) Annual Meeting and Scientific Session in Philadelphia this week.
The study, published in Nature Medicine, shows that a heart from a donor with Type A blood can successfully be transplanted into an infant with Type O blood. Unlike older children and adults, babies do not yet have the antibodies that would normally reject antigens from a different blood type.
"The baby's body educates itself to accept the organ and become tolerant of the blood type," says Lori West, MD, a pediatric cardiologist at the Hospital for Sick Children in Toronto and co-author of the study.
The body's tolerance of a donor organ has always been one of the greatest challenges of transplant medicine. A cardinal rule is that a transplant from a mismatched donor results in the recipient rejecting the organ.
"The medical community has been trained that you just don't cross that blood group barrier," says West. "For the first time, we have shown that the immune systems of human infants can tolerate intentional induction of B-cells to T-independent A and B antigens," says West. Other combinations have proved successful as well: "We have induced Type B to Type O, AB to O, A to B, etc., all with excellent results."
Many babies who undergo heart transplantation require a second donor heart at some point. The results of the study show that because the immune cells that would normally respond and attack the donor organ were eliminated with the first transplant, the patient can again receive a donor heart from that same blood type.
Known as the Toronto Protocol, the study originally involved fetal and infant mice and la
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Contact: Susan Speer
sspeer@masonpr.com
210-678-9248
International Society for Heart and Lung Transplantation
4-Apr-2005