New Method Improves Renal Transplant Biopsy Accuracy

Molecular measurements allow for more accurate classification of borderline rejection biopsies

MONDAY, Oct. 24 (HealthDay News) -- Adding molecular phenotyping to histological classification of kidney transplantation biopsies facilitates more accurate classification of borderline rejection biopsies, and helps eliminate this category in most cases, according to a study published online Oct. 12 in the American Journal of Transplantation.

Declan G. de Freitas, M.D., from the University of Alberta in Edmonton, Canada, and colleagues examined the nature of borderline biopsies in an attempt to eliminate the borderline histological category in the current Banff classification of inflamed biopsies in kidney transplantation. They investigated the molecular changes in 40 borderline, 35 T-cell-mediated rejection (TCMR), and 116 nonrejection biopsies, using microarrays to assess T-cell burden, a rejection classifier, a canonical TCMR classifier, and risk score.

The investigators found that assessment of the molecular changes reassigned 33 percent of borderline biopsies as TCMR-like, and 67 percent as nonrejection-like. Atrophy-scarring, which interferes with assessment of inflammation and tubulitis, was a major reason that histology diagnosed molecularly-defined TCMR biopsies as borderline. However, in 85 percent of cases reviewed using decision tree analysis, an all cortical inflammation greater than 27 percent and tubulitis extent of greater than 3 percent matched the molecular diagnosis of TCMR.

"Most cases designated borderline by histopathology are found to be nonrejection by molecular phenotyping. Both molecular measurements and histopathology offer opportunities for more precise assignment of these cases after clinical validation," the authors write.

The study was partially funded by Novartis, Bristol-Myers Squibb, and Genome Canada. One of the study authors disclosed financial ties to Transcriptome Sciences Inc., which has an interest in molecular diagnostics.

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Physician's Briefing

Published on October 24, 2011

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