The role of electron microscopy (EM) in diagnosis of AMR is not well-defined. We sought to examine the EM findings in 796 biopsies from 622 adult recipients performed between July 2010 and Oct 2014. Median time to biopsy was 12.6 mo from transplantation [IQR:4.2-32.5].

* % of biopsies.

EM parameters in the first biopsy that were associated with graft survival included' extensive glomerular endothelial cell-swelling (GECS) (HR:3.1, P=0.001, CI:1.6-5.8) and podocyte effacement (HR:2.7, P=0.003, CI:1.4-5.3), Subebdothelial_expansion/GBM reduplication (SEE/GBMR) (HR:2.4, P=0.001; CI:1.4-4.1), and PTC BM multilayers (ML)>3 (HR:3.3, P<0.001, CI:1.9-5.6). Among these variables PTCBMML>3 was independently predictive of graft failure (HR:2.2, P=0.02; CI:1.1-4.2), and extensive GECS had borderline association (HR:1.8, P=0.07, CI:0.95-3.4); both were strongly associated with the number of DSA specificities (OR:3.5, P<0.001, CI:2.5-4.9; HR:4.4, P<0.001, CI:3.3-6, respectively).

In this cohort, 11.1% of the DSA-negative biopsies and 14.9% with DSA had no light microscopic (LM) features of AMR but had extensive GECS in EM; SEE/GBMR was observed in 7.6% and 8.4%, respectively.

The results of this study show that EM features are strongly associated with DSA and strong predictors of graft outcome. In the absence of LM features of AMR, these EM features could be helpful in recognizing AMR, particularly in the absence of DSA.

CITATION INFORMATION: Haririan A, Chaudhry M, Papadimitriou J, Costa N, Thomas B, Mavanur M, Ugarte R, Cangro C, Drachenberg C. Association of Ultrastructural Changes in Renal Allograft Biopsies with Antibody-Mediated Rejection (AMR) and Graft Outcomes. Am J Transplant. 2016;16 (suppl 3).

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