Diagnosis of acute rat renal allograft rejection with 18F-FDG labeled T-lymphocytes and positron emission tomography

593 Objectives Aim of this study was to evaluate the suitability and specificity of positron emission tomography (PET) with ex vivo 18F-fluorodeoxyglucose (18F-FDG)-labeled T-lymphocytes for the detection of acute rejection (AR) after rat renal transplantation. Methods 18F-FDG labeled T-lymphocytes were injected into adult uni-nephrectomized allogeneically transplanted rats (LBN to Lewis) on post operative day 4. Tissue activity was quantitatively assessed in vivo by a small animal PET scanner and percentage of injected dose (%ID) was compared between graft and native kidney. In vivo results were confirmed by autoradiographic and RT-PCR analyses and histological stainings. Syngeneically (sTX) transplanted rats (LBN to LBN), rats with ischemia-reperfusion injury (IRI, 45 min warm ischemia), and with acute cyclosporine A (CSA) toxicity (50 mg/kg for 2 days i.p.) served as controls. Results Infiltration of radiolabeled T-cells was significantly elevated in renal allografts (1.18 ± 0.32 %ID) with signs of AR when compared to native control kidneys (0.44 ± 0.15 %ID). Moreover, there was no increased 18F-FDG-uptake found in sTX rats (0.61 ± 0.14 %ID), rats with acute CSA toxicity (0.39 ± 0.18 %ID) and kidneys with IRI (0.40 ± 0.20 %ID). In vivo results correlated well with results obtained by autoradiography and RT-PCR as well as histological analysis. Conclusions We herein present an entirely image-based technique to non-invasively and early detect AR and differentiate it from acute tubule necrosis. PET with radiolabeled T-lymphocytes is potentially clinically useful to investigate the kinetics of AR in humans as well as the response to therapeutic interventions, while simultaneously reducing the patient’s exposition to radiation due to the low dose of 18F-FDG needed for T-lymphocyte labeling and imaging