Microvascular Inflammation of Kidney Allografts and Clinical Outcomes.
Across 16,293 kidney-transplant biopsy specimens from 6,798 patients, the two microvascular inflammation categories newly recognized in the Banff 2022 classification identified distinct rejection phenotypes carrying a higher risk of graft loss and transplant glomerulopathy - most of them previously classed as showing no evidence of rejection.
Background
The heterogeneous clinical presentation of graft microvascular inflammation poses a major challenge to successful kidney transplantation, and the effect of microvascular inflammation on allograft outcomes had been unclear. The 2022 Banff Classification of Renal Allograft Pathology introduced two new diagnostic categories: probable antibody-mediated rejection, and microvascular inflammation without evidence of an antibody-mediated response.
Study design
This was a cohort study of kidney-transplant recipients from more than 30 transplantation centres in Europe and North America who had undergone allograft biopsy between 2004 and 2023. Clinical and pathological data were integrated to classify biopsy specimens according to the 2022 Banff classification, and the association between the newly recognized microvascular inflammation phenotypes and allograft survival and disease progression was then assessed.
Key findings
A total of 16,293 biopsy specimens from 6,798 patients were assessed. The newly recognized microvascular inflammation phenotypes were identified in 788 specimens, of which 641 had previously been categorized as showing no evidence of rejection. Compared with patients without rejection, the hazard ratio for graft loss was 2.1 (95% CI 1.5 to 3.1) for microvascular inflammation without evidence of an antibody-mediated response and 2.7 (95% CI 2.2 to 3.3) for antibody-mediated rejection. Patients with probable antibody-mediated rejection had a higher risk of graft failure beyond year 5 after biopsy (hazard ratio 1.7; 95% CI 0.8 to 3.5). Both newly recognized phenotypes carried a higher risk of transplant glomerulopathy progression during follow-up.
Clinical implications
Microvascular inflammation in kidney allografts comprises distinct phenotypes with differing disease progression and allograft outcomes. The authors concluded that these findings support the clinical use of the additional rejection phenotypes to standardize diagnostics for kidney allografts. The study was funded by OrganX (ClinicalTrials.gov NCT06496269).
Category
Transplant
Source
N Engl J Med
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