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 group is defined as :  Histological lesions of tubular injuries in the absence of significant microvascular inflammation or C4d deposits No detectable anti-HLA DSA at the time of biopsy  Exclusion Criteria:  Minor patients Mixed rejection (antibody-mediated and T cell-mediated) Recurrent or de novo nephropathy Specific treatment of rejection (T cell-mediated or antibody-mediated) in the last 6 months, excluding induction and Baseline immunosuppressive treatment.