Signs of Rejection

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Science  15 Apr 2011:
Vol. 332, Issue 6027, pp. 284
DOI: 10.1126/science.332.6027.284-b

Recipients of heart transplants are treated with powerful immunosuppressants to prevent organ rejection, but complications still occur. Early signs of rejection are often monitored by an invasive procedure that requires heart tissue biopsy. A noninvasive diagnostic test was recently approved in the United States, in which blood cells from heart transplant recipients are monitored for the expression of genes associated with immune-mediated rejection.

Snyder et al. have designed a potentially complementary noninvasive test based on the concept that during organ rejection, dying cells in the organ release donor DNA that might be detectable in the recipient's bloodstream by high-throughput sequencing methods. In a small proof-of-principle study of archived blood samples from heart transplant recipients, the authors showed that the level of cell-free donor DNA in the recipient's blood increased substantially when there was an acute cellular rejection episode and then declined again once the patient received more aggressive treatment. Although an encouraging start, the predictive value of this test will become clear only from much larger studies in which its performance is compared with that of biopsies and with conventional clinical measures of heart function, such as echocardiograms.

Proc Natl. Acad. Sci. U.S.A. 108, 10.1073/pnas.1013924108 (2011).

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