Annexin-V imaging for noninvasive detection of cardiac allograft rejection

Heart transplant rejection is characterized pathologically by myocyte necro sis and apoptosis associated with interstitial! mononuclear cell infiltrati on. Any one of these components: can be targeted for noninvasive detection of transplant rejection. During apoptotic cell death, phosphatidylserine, a phospholipid that is normally confined to the inner leaflet of cell membra ne bilayer, gets exteriorized. Technetium-99m-labeled annexin-V, an endogen ous protein that has high affinity for binding to phosphatidylserine, has b een administered intravenously for noninvasive identification of apoptotic cell death. In the present study of 18 cardiac allograft recipients, 13 pat ients had negative and five had positive myocardial uptake of annexin. Thes e latter five demonstrated at least moderate transplant rejection and caspa se-3 staining, suggesting apoptosis in their biopsy specimens. This study r eveals the clinical feasibility and safety of annexin-V imaging for noninva sive detection of transplant rejection by targeting cell membrane phospholi pid alterations that are commonly associated with the process of apoptosis.