Bacteria In Donor Organs Complicate Immune Response After Transplantation

Arthur T Knackerbracket has processed the following story:

Organ transplant recipients take life-long immunosuppressive drugs to prevent their bodies from mounting an immune response against the donated organ, yet a substantial number of them still reject the organs. A new study by researchers from the University of Chicago shows that transplant recipients also mount an immune response against commensal bacteria in the organ graft, adding to the immune response against the genetic makeup of the tissue and reducing the effectiveness of immunosuppressive drugs.

The study, published today in the Journal of Clinical Investigation, also shows that this anti-microbial immune response can be triggered by immune cell memory of previous encounters with bacteria, further complicating the body's ability to accept a lifesaving new organ.

"Before, we thought the reason why transplanted organs in humans are less easily accepted than in sheltered laboratory animals is that humans can have immune memory responses that cross-react on the cells of the organ, and memory responses are more difficult to suppress with drugs than naive responses," said Maria-Luisa Alegre, MD, PhD, Professor of Medicine at UChicago and senior author of the study. "Now, we see that it's not only memory cells that recognize the organ itself that are the problem, but also memory responses that recognize bacteria in the organ."

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