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Abstract: SA-PO1058

Isolated Glomerulitis Is Associated with the Absence of Molecular Antibody-Mediated Rejection (ABMR) in Cases with Histologically Suspected and Confirmed ABMR

Session Information

Category: Transplantation

  • 2102 Transplantation: Clinical

Authors

  • Schachtner, Thomas, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Weidmann, Lukas, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Harmacek, Dusan, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Bortel, Nicola, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • López, Kai Castrezana, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Korach, Raphael, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Mueller, Thomas F., UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
Background

According to the 2018 Banff classification, the Molecular Microscope Diagnostic System (MMDx) is indicated in cases when histology is insufficient to diagnose antibody-mediated rejection (ABMR) due to an absence of diagnostic criteria groups 2 (antibody interaction with tissue) and/or 3 (DSA and equivalents). The impact of isolated glomerulitis (g>0, ptc0) on the likelihood of molecular ABMR appears critical to the implementation of this new biomarker.

Methods

We analyzed 326 kidney allograft biopsies by histology and MMDx at the University Hospital Zurich. Histologic findings were classified into: (1) 30 cases with suspected ABMR: isolated mild glomerulitis (g1), DSA-, (2) 32 cases with suspected ABMR: isolated mild glomerulitis (g1), DSA+, (3) 33 cases with suspected ABMR: MVI (g+ptc>1), DSA-, (4) 60 cases with confirmed ABMR: MVI (g+ptc>1), DSA+.

Results

MMDx diagnosed ABMR in 5/30 cases (17%) with isolated g1 without DSA, 12/32 cases (38%) with isolated g1 with DSA, 18/33 cases (55%) with MVI without DSA, and 30/60 cases (50%) with histologically proven ABMR. While only 17/65 cases (26%) with molecular ABMR showed isolated glomerulitis, 64/90 cases (71%) without molecular ABMR showed isolated glomerulitis (p<0.001). Among cases with isolated glomerulitis, molecular ABMR was detected more frequently in cases with proteinuria (p=0.011), the presence of DSA (p=0.033), and transplant glomerulopathy (cg; p=0.014).

Conclusion

MMDx confirms ABMR in a relevant proportion of cases with isolated mild glomerulitis. However, isolated glomerulitis is associated with the absence of molecular ABMR in cases with suspected and confirmed ABMR. Proteinuria, DSA, and transplant glomerulopathy are associated with molecular ABMR among cases with isolated glomerulitis.

Funding

  • Private Foundation Support