Infants under 1-year can accept heart transplants from doors of different blood groups.
A heart from a donor with Type A blood can be successfully transplanted into an infant with Type O blood because unlike older children and adults, babies do not yet have the antibodies that would normally reject antigens from the different blood types, reported Lori West, MD, a pediatric cardiologist at the Hospital for Sick Children in Toronto, Canada, and co-author of the study. "The baby's body educates itself to accept the organ and become tolerant of the blood type," explained West.
"The medical community has been trained that you just don't cross that blood group barrier," West added. "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. We [also] have inducted Type B to Type O, AB to O, A to B, etc., all with excellent results."
The study, which is known as the Toronto Protocol, originally involved fetal and infant mice, then human babies, whose progress was tracked for more than 8 years. The protocol has now been adopted at 15 medical centers worldwide with similar successes reported at each center.
"This knowledge will save lives," West said. "More babies will survive congenital heart defects and go on fulfilling lives with a donor heart. We can use this knowledge to decrease the amount of time a patient must wait for a new heart-we'll be able to use donor organs more efficiently and perform increasingly successful transplants."
The tolerance of the donor organ also makes it easier for babies to get a 2nd transplant when the first one rejects, which happens often in children. The study showed 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.
The results of the study, which was published in Nature Medicine, were presented at the 25th annual meeting of the International Society for Heart and Lung Transplantation (ISHLT).
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|Date:||Apr 28, 2005|
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