Isolated” v “ Lesions May Reflect Both Cellular or Humoral Rejection.

Abstract

Background: In kidney transplantation, intimal arteritis or “ v “ lesion is a marker of severe prognosis, usually seen with tubulo-interstitial inflammation in T cell mediated rejection (TCMR) or with microcirculation inflammation in antibody mediated rejection (ABMR). Isolated “ v “ lesions, defined by the absence of associated microcirculation or interstitial inflammation, are rare and their significance is matter of debate. Methods: We retrospectively reviewed the pathology files (from September 2004 to may 2013) from 3 University Hospitals to identify kidney biopsies (KB) with isolated v lesions, defined by v≥1, i≤1 and g+ptc≤1 according to the Banff classification. Patients without available serum for Donor Specific Antibodies (DSA) testing were excluded. DSA were assessed by Luminex© single antigen assay. The clinical, biological and histological outcomes were reviewed with a mean follow up of 3.8±2.5 years. Results: 30 patients (men 70%, 52±12 y) had isolated v lesions. All but 1 KB were performed during the first year post-transplant (median 22 days), either in protocol (n=8, 27%) or for cause (73%) KB. Half were performed within the first month for acute renal failure or delayed graft function. V lesions included 24 cases of v1 (80%), 3 v2 and 3 v3 (10%) lesions. Nine isolated v lesions (30%) were associated with DSA. In these cases, only one was C4d+. Six out of these 9 patients were treated [ABMR-treatment (n=4) or TCMR treatment (n=2)] and 4 (44%) had a bad outcome defined by graft loss (n=2) or patient death (n=2). In the 21 DSA negative patients, 16 received a TCMR-treatment and 5 were not treated. Among these 21 patients, 4 (19%) had a bad outcome (graft loss, n=3 or death n=1) and 8 (38%) had TCMR lesions and/or progression of Interstitial Fibrosis/Tubular Atrophy in subsequent biopsies. Conclusion: Isolated v lesions are mainly observed in for cause KB within the first year post-transplantation. Isolated v lesions represent a heterogeneous group that may reflect both TCMR and ABMR. 30% are associated with DSA and with a bad outcome. This study suggests that DSA status should be determined in case of isolated v lesion for adapted treatment.