Date: Tuesday, May 2, 2017
Session Name: Poster Session D: Diagnostics/Biomarkers Session II
Session Time: 6:00pm-7:00pm
Presentation Time: 6:00pm-7:00pm
Location: Hall D1
Deposition of C4d has been an established part of the Banff classification scheme for antibody mediated rejection (AbMR) since 2001. More recently, C4d negative AbMR has been described but the presence of C4d remains a highly specific marker for AbMR. However, a small sub-set of patients with C4d positive biopsies have no histological features of inflammation and donor specific antibodies are not always present. ABO incompatible (ABOi) accommodated transplants also frequently stain positive for C4d. Our aim was to investigate these patients to understand the significance of C4d staining in otherwise normal biopsies.
RNA was extracted from formalin fixed paraffin embedded biopsies and gene expression analysis of 96 transcripts in 84 patients was carried out using the Nanostring nCounter system. Genes were chosen based on published microarray data. Samples included AbMR, TCMR, Normal, stable ABO incompatible and the study group of C4d positive samples with no inflammation.
Many genes showed widespread expression levels in the study group. Interferon-gamma induced C-X-C motif chemokines 10, 11 and 13 demonstrated reduced expression in normal, ABOi and C4d positive study group samples, when compared to rejecting samples. However, IFNG itself was elevated in some C4d positive samples. Reduced expression in the study group was also observed for GNLY, PLA1A and TRD, all associated with AbMR, and EV12A and PTPRC, injury repair response associated genes. Expression levels were comparable to normal and ABOi samples.
Elevation of IFNG without chemokine elevation suggests rejection is initiated but subsequently blocked, in much the same way as accommodated grafts appear to block the complement cascade after C4d deposition. The spread of expression levels within the C4d positive group suggests a heterogeneity not yet fully defined. Following up these patients to determine which develop AbMR is crucial to furthering our understanding of the rejection process.
CITATION INFORMATION: Dominy K, Willicombe M, Al Johani T, Galliford J, McLean A, Cook T, Roufosse C. Assessment of C4d Positive Biopsies with No Histological Evidence of Inflammation Using Nanostring nCounter Technology. Am J Transplant. 2017;17 (suppl 3).
To cite this abstract in AMA style:Dominy K, Willicombe M, Johani TAl, Galliford J, McLean A, Cook T, Roufosse C. Assessment of C4d Positive Biopsies with No Histological Evidence of Inflammation Using Nanostring nCounter Technology. [abstract]. Am J Transplant. 2017; 17 (suppl 3). https://atcmeetingabstracts.com/abstract/assessment-of-c4d-positive-biopsies-with-no-histological-evidence-of-inflammation-using-nanostring-ncounter-technology/. Accessed June 5, 2020.
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