P119 Single-center experience in routine post-transplant antibody testing of kidney transplant recipients without pre-existing donor specific anti-HLA antibodies

Abstract

Aim Antibody-mediated rejection (AMR) of kidney allografts is thought to follow a stepwise process which includes alloimmune recognition, followed by microscopic changes (subclinical rejection) and then allograft dysfunction (clinical rejection). There is data to suggest that development of de novo donor-specific antibodies (DSA) is associated with subclinical and clinical rejection. Following a recent expert consensus guideline, we implemented routine post-transplant antibody testing for patients to capture de novo DSA to determine how often we detected de novo DSA and whether we could use de novo DSA in the clinical decision making process. Methods The Beth Israel Deaconess Medical Center Transplant program instituted routine post-transplant antibody testing in mid-2014. The frequency of post-transplant antibody testing was determined based on the presence or absence of DSA against kidney allograft. Patients without pre-existing DSA, based on cumulative pre-transplant testing, were considered low-risk for AMR and routinely tested at one year post-transplant for de novo DSA by multiplex bead array solid phase antibody screen. Results From May 2014-June 2015, 84 patients received a kidney allograft, 69 (82%) of whom were considered low-risk (i.e. no DSA ever detected by serial pre-transplant testing). Of the 69 low-risk patients, five patients were not tested for antibody at one-year post-transplant. Four of 64 (6%) low-risk patients were found to develop de novo DSA by one-year post-transplant. In three patients, there was concomitant proteinuria or elevated creatinine found at the time of post-transplant antibody testing. Two of three suffered AMR; one had chronic allograft changes. The fourth patient with de novo DSA had stable kidney function and is being monitored. Conclusions We detected de novo DSA in 6% of low risk renal transplant recipients with routine post-transplant monitoring at one year post-transplant. In three patients, there was concomitant laboratory findings of allograft dysfunction which prompted allograft biopsy. Further studies have to be performed to determine the optimal timing of routine antibody testing in low-risk patients after kidney transplantation.