Background: Peritubular capillaritis (PTC) is a part of microvascular inflammation seen in antibody-mediated rejection. However, it can be observed as an isolated lesion in early transplant kidney biopsies with little known about its significance. We aimed to investigate molecular significance of PTC in early kidney transplant biopsies of patients without donor-specific antibody (DSA).

Methods: We identified 19 early transplant kidney biopsies performed within 6 months after transplantation for gene expression profiling comparing to 12 normal transplant biopsies with all acute and chronic Banff allograft injury score of 0. Biopsies with a diagnosis of acute or chronic rejection, recurrent or de novo glomerular disease, moderate to severe fibrosis (chronic sum score ci+ct+cv > 4) or polyoma nephropathy were excluded. The gene expression profiles were studied by Affymetrix HuGene 1.0 ST expression arrays.

Results: Of the 19 biopsies studied, 7 patients had isolated PTC and 12 patients had no PTC. The PTC score was 1 in 6 patients and 2 in one patient. Both groups had similar demographics characteristics in terms of age, race, and sex, type of transplant, previous history of transplantation or acute rejection, donor characteristics, panel reactive antibody levels and immunosuppressive treatment. Mean Banff allograft injury score was also similar between the 2 groups (1.5 ±1.50 vs. 2.2 ± 1.38). There was no statistically significant difference in gene expression profiles between the groups including injury and response (IRIT), interferon-gamma and rejection (GRIT), cytotoxic T cell (CAT), regulatory T cell (TREG), B-cell (BAT), Constitutive Macrophage (CMAT), donor-specific antibody (DSAST) and endothelial cell associated transcripts

.

Conclusions: Isolated peritubular capillaritis could be seen in early transplant kidney biopsies and intragraft gene expression profiles do not reflect immune activity.

CITATION INFORMATION: Ajaimy M, O Broin P, Bao Y, Akalin E. Molecular Significance of Peritubular Capillaritis in Early Transplant Kidney Biopsies of Donor-Specific Antibody Negative Patients. Am J Transplant. 2017;17 (suppl 3).

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