Antibody monitoring in pancreas transplantation: When should we biopsy?

UVA PD; QUEVEDO A; DOTTA A; TONIOLO F; CHULUYAN E; CASADEI D

Congreso; 27th International Congress of The Transplantation Society TTS; 2018

The Transplantation Society - TTS

Introduction: In kidney transplantation de novo donor-specific HLA antibodies(DSA) have been found to correlate to poor graft survival and ConsensusGuidelines recommend a protocol biopsy. In pancreas transplantation DSAhad also been associated with poor graft outcomes however there are no recommendationson protocol biopsies. In June, 2013 a screening protocol wasinitiated for detection of anti-HLA antibodies (Abs) by Luminex. Testing wasperformed on patients presenting with dysfunction and by protocol at 0, 3,6, 12 months and yearly for new transplants and yearly for previous transplants.Patients with DSA Abs and patients with high MFI non-DSA Abs wereconsidered for protocol biopsy of both organs.Results: During the study period 144 pancreas transplant recipients werescreened for anti-HLA antibodies. 106 patients had initially negative antibodiesand 20 among them produced de novo antibodies. 38 had positive antibodiesat the initial testing.86 patients had negative antibodies though the study period.Among them10 presented dysfunction and biopsy proven rejection of either organ duringfollow-up, being 8 acute cellular rejections (ACR) and 2 antibodymediated rejections(AMR).There were 20 patients with initially negative Abs that presented de novoAbs during follow up. Seven of these were found to have positive Abs whenpresenting with rejection (all non-DSA Abs). The other 13 cases were detectedby screening. Among these, there were 7 non-DSA and 6 DSA cases.No biopsieswere performed in the non-DSA caseswith 1 presenting rejectionat 3 years of follow-up. All 6 patients with DSA Abs had protocol biopsies with2 of them showing subclinical kidney AMR.We found 38 patients with positive Abs at the initial testing. 10 of themwere detected when presenting with dysfunction and all were biopsied.Among these, 5 had DSA and 5 non-DSA Abs and all but one patient hadrejection. The other 28 cases were detected by screening. In this group,18 patients had non-DSA Abs and 8 of them were biopsied with negativeresults and remained rejection free. The last 10 cases had DSA Abs initially.Six of them were biopsied and had subclinical rejection on the kidney (3),the pancreas (1) or both (2). Of the remaining four patients without biopsy,2 presented kidney humoral rejection during at 6 and 12 months of followupand 2 remained rejection free.Discussion: Our protocol detected 40% of patients with positive anti-HLAAbs (26% at the initial testing and 14% de novo during follow-up) with 36%of them beingDSA abs. In non-dysfunctioned patientswith non-DSA abs protocolbiopsieswere negative in all biopsied patients and only 4% of them presentedrejection during follow-up. In contrast, in non-dysfunctioned patientswithDSAabs protocol biopsies found subclinical rejection in 66% of them and half thenon-biopsied patients presented rejection during follow-up.We conclude thatpatients with DSA abs may benefit from protocol biopsies of both grafts.