The clinical and genomic significance of donor-specific antibody (DSA) positive/C4d negative and DSA negative/C4d negative transplant glomerulopathy

We investigated the clinical, histopathologic and genomic features of donor-specific antibody (DSA) +/C4d- and DSA-/C4d- transplant glomerulopathy (TGP) using microarrays. Comparison of the gene expression profiles of DSA-/C4d- TGP biopsies with ptc+g score > 1 to normal and IFTA (Interstitial Fibrosis and Tubular Atrophy) biopsies by microarrays revealed increased expression of quantitative cytotoxic T cell--associated transcripts (QCAT). However, CAMR (chronic antibody-mediated rejection) and DSA+/C4d- TGP had increased expression of QCAT, interferon-gamma and rejection induced, constitutive macrophage-associated, natural killer cell-associated, and DSA selective transcripts. B cell and endothelial cell associated transcripts expression were upregulated only in CAMR biopsies. Our results suggest that while DSA+/C4d- TGP should be classified under CAMR, DSA-/C4d- TGP with ptc+g score > 1 probably develops through a chronic cellular immune response. Total of 57 arrays included in this study. G1. Normal transplant kidney biopsies (N= 12); G2. Non-specific IFTA (N= 17); G3. TGP DSA-/C4d- (N=8); G4. TGP DSA+/C4d- (N= 9); G5. CAMR/TGP C4d+/DSA+ (N= 11)