Objective: Molecular evidence of allograft injury might precede histopathological findings of allograft injury. We aimed to investigate if the type of induction therapy effect intragraft gene expression profiles of early normal transplant kidney biopsies.

Methods: We identified 34 near normal biopsies performed at our center within 6 months of transplant between 2009 and 2012 for gene expression profiling. Biopsies with a diagnosis of acute rejection (Banff t score >0, v score >0), recurrent or de novo glomerular disease, or polyoma nephropathy were excluded. The gene expression profiles were studied by Affymetrix HuGene 1.0 ST expression arrays.

Results: Of the 34 kidney biopsies, 17 patients received anti-thymocyte globulin for class I or II panel reactive antibody (PRA) levels > 20% and 17 had PRA<20% and inducted with basiliximab. There was no difference in recipient age, sex, type of transplant, etiology of kidney disease or donor age and sex between the 2 groups. Although, the mean cold ischemia time was longer (24.6 ±14 vs. 18.8 ±11.5 hours, p=0.26) and the delayed graft function was more prevalent (76% vs 50%, p=0.08) in the basiliximab group, the difference was not statistically significant. As expected, the median class I 70% (18,100) and II 35% (2,100) PRA levels were higher in anti-thymocyte group compared to basiliximab group, median class I 5%( 0,14) and II 7(0,17) PRA, respectively. There was no difference in Banff acute allograft injury scores including microvascular inflammation (glomerulitis and peritubular capillaritis), interstitial inflammation, or chronic injury scores (cg, ct, ci, cv and mm) between the 2 groups. There were no differentially expressed genes between the two groups (Both False discovery rate p<0.05 and fold change >2). Pathogenesis based transcripts showed no difference in the expression of intragraft gene transcripts associated with Cytotoxic T-cells, Regulatory T cells, B cells, Natural-Killer cells, Macrophage, Endothelial cells and Interferon-gamma and rejection induced transcripts between the 2 groups.

Conclusions: Despite the anti-thymocyte globulin treated patients are immunologically higher risk than basiliximab treated patients; there was no difference in intragraft gene expression profiles or Banff allograft injury scores of early kidney biopsies between the 2 groups

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