Xenotransplantation survival

CMAJ 2000;163(8):1032

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Arrows indicate vessels, diseased (left) and healthy (right), in rat heart grafts transplanted into mice.

Mice with high levels of the 2 cytokines took an average of 24 days to reject grafted rat hearts, compared with just 6 days for mice with a cytokine deficiency.

"This changes the emphasis," says David Kelvin, an immunologist at the Robarts Research Institute and the University of Western Ontario. "Before, we had thought that these molecules were a negative influence on the survival of allografts. We found that these molecules have a beneficial effect in xenograft rejections."

The cytokines were found to regulate acute vascular rejection (AVR), considered the major obstacle to successful xenotransplants. Although researchers have largely overcome the initial hyperacute rejection of xenografts, AVR sets in within days, destroying the organs within weeks or months.The prospect of regulating AVR without antirejection drugs could lead to new therapeutic strategies for controversial pig-to-human transplants. As both g interferon and interleukin-12 are present in humans, the new findings point to a possible "genetic starting point" for preventing or minimizing graft rejection, the authors say. — David Helwig, London, Ont.

Copyright 2000 Canadian Medical Association or its licensors