Can Heart Allografts Protect Simultaneous Kidney Allografts from Antibody Injury?

Abstract

<h3>Purpose</h3> Pre-formed donor specific antibodies (DSA) are associated with antibody mediated rejection (AMR) and graft loss in kidney transplants. However, simultaneous liver/kidney transplants show a lower risk for DSA mediated AMR in kidney allograft, likely due to absorbance of DSAs by the liver allograft. The goal of this study is to determine if heart allografts can protect subsequent kidney grafts from antibody mediated injury. <h3>Methods</h3> 93 patients were transplanted with combined heart and kidney allografts between 2016 and 2020 at our center. The median time (interquartile range [IQR]) of post-transplant follow up is 883 days (459-1322). Treatment for patients transplanted across DSA included intravenous immune globulin, obinutuzumab, and eculizumab. <h3>Results</h3> 12 of 93 recipients had pre-formed DSA, with 3 recipients having strong pre-formed DSA (MFI>10,000); 5 recipients having moderate DSA (MFI >5,000); 4 recipients having weak DSA (MFI>2,500). Survival was not different between recipients with preformed DSA and recipients without preformed DSA (p=0.436) (Fig. 1). Of these 12 patients with pre-formed DSA, 4 patients had positive flow crossmatches and were treated with intravenous immune globulin. Notably, one of these 4 patients also had a positive CDC crossmatch with pre-formed C1q-binding DSA and was treated with obinutuzumab and eculizumab in addition to intravenous immune globulin. All 4 patients had stable renal and cardiac function at the end of the follow up. DSA in 3 of these 4 patients including the patient with positive CDC crossmatch, became negative during the follow up (Fig. 2). <h3>Conclusion</h3> Levels of DSA can decrease post heart/kidney transplant, suggesting the heart/kidney transplant may modulate antibody response. Our study indicates that the kidney can be transplanted across strong DSA in heart/kidney combined transplant with acceptable outcomes.