Mass Spectrometry-based Proteomics in Microvascular Inflammation Diagnosis in Kidney Transplantation.

Inclusion Criteria: * Kidney transplant recipients * Diagnosis based on the 2019 Banff classification (polyomavirus nephropathy, T cell-mediated rejection, borderline changes) * Renal allograft biopsy allowing inclusion with at least 7 permeable glomeruli * The microvascular inflammation group with anti-HLA DSA is defined as follows: * At least moderate microvascular inflammation: g + ptc \> 2 * At least one anti-HLA DSA in the serum at the time of biopsy, with a Mean Fluorescence Intensity (MFI) \> 3000 for the immunodominant DSA or the sum of the DSA * The microvascular inflammation group without anti-HLA DSA is defined as follows: * At least moderate microvascular inflammation: g + ptc \> 2 * No historical anti-HLA DSA or at the time of biopsy, MFI \< 500 * The stable graft recipients group is defined as follows: * Glomerual Filtration Rate \> 40ml/min, without clinical proteinuria * No detectable DSA * Protocol biopsy at 1 year posttransplantation without specific lesion or nonspecific severe lesion * The chronic nonspecific graft changes group is defined as follows: * Moderate to severe interstitial fibrosis and tubular atrophy, in the absence of specific lesions: active rejection (antibody-mediated or T cell-mediated), borderline lesions, recurrent or de novo nephropathy, polyomavirus associated nephropathy. * No C4d deposits on peritubular capillaries * No detectable anti-HLA DSA at the time of biopsy. * The ischemic acute tubular injuries grou…