Believe it or not it's been 40 years since the first human to human heart transplant was performed by Christiaan Barnard in South Africa. The success of this procedure is now attested to by the fact that over 2000 patients in the United States receive a heart transplant each year with an estimated 50% 10 year survival. In 1967 the first patient to receive a heart transplant survived only 18 days.
One of the main medical concerns following heart transplantation is rejection of the organ by the recipient immune system. A new test, AlloMap, is now available that can detect the presence of cardiac rejection noninvasively [Starling RC et al., J Heat Lung Transplant, 25:1389, 2006]. The test is based on the measurement of expression of certain genes in peripheral blood mononuclear cells. A panel of 11 genes is reliably informative for the identification of patients who have a very low risk of organ rejection. While the negative predictive value of the test is extremely high the positive predictive value is quite low, in part because of the fact that with modern immunosuppressive therapies, relatively few patients develop acute cellular rejection particularly after more than a year post-transplantation. It is possible that the new test will reduce the number of cardiac biopsies that are performed posttransplantation. If so, this will be probably be welcomed by patients.
Presumably the AlloMap test will be applied to other organ transplants such as liver, kidney and lung. At the time of the first human heart transplant the procedure seemed extraordinary. In many ways, the ability to detect organ rejection by gene expression profiling in a blood sample seems equally extraordinary.
