The researchers screened 200 transplant recipients and their organ donors for the genetic makeup of TLR4, or "toll-like receptor 4," a key component of innate immunity. Two variants of the gene had earlier been linked to a reduced lung response to bacterial toxins.
Recipients with a single copy of either of those two TLR4 variants exhibited a reduced rate of acute rejection during a period of six months after surgery, the researchers found. Specifically, acute rejection occurred in 28 percent of recipients with the relevant TLR4 variants compared to 58 percent of recipients with more common forms of the gene. The innate immunity genes of the donor had no effect on the chances of rejection, they reported.
The long- and short-term survival of patients after lung transplant lags behind that of other transplanted organs, Palmer said. The new study suggests that the strong innate immune response in the lung might help to explain that difference, he added.
"Innate immunity is critical in the lungs because the organ has to deal constantly with inhalational exposures, including infectious agents and environmental toxins," Palmer said. "Therefore, the lung has an incredible array of innate defenses, including immune cells with receptors like TLR4 built in to recognize and respond to foreign pathogens. Further understanding their role in transplant should greatly enhance physicians' ability to prevent and treat clinical rejection."
The team will conduct additional studies to further elucidate the interaction between the innate and adaptive immune systems following organ transplantation.
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Contact: Kendall Morgan
kendall.morgan@duke.edu
919-684-4148
Duke University Medical Center
24-May-2004