Transplantation proceedings · 2026
Clinical and Histological Phenotypes of Antibody-Mediated Rejection in Kidney Transplant: A Single-Center Experience from Latin America.
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Noboa Javier, Astesiano Rossana, Santiago Jose, Noboa Agustin, Marton Sebastian, Lorenzo Mariana, Coitiño Ruben, Noboa Oscar, Nin Marcelo, Tiscornia Adriana, Seija Mariana
Аннотация
BACKGROUND: Antibody-mediated rejection (AMR) is a major cause of kidney allograft failure. A substantial proportion of AMR occurs without detectable donor-specific antibodies (DSA), and the clinical relevance of DSA-negative AMR remains incompletely defined, particularly in regions with limited access to advanced immunological testing.
METHODS: We conducted a retrospective analysis of kidney transplant recipients at a single center in Uruguay between 2018 and 2024. Patients with for-cause biopsies fulfilling contemporary Banff criteria for active AMR were included; chronic active AMR and non-immunologic lesions were excluded. Donor-specific antibodies were assessed at the time of biopsy using class I and II screening assays. Clinical, histological, and outcome data were compared between DSA-positive and DSA-negative AMR. Quantitative histological analyses, including an AMR/MVI index and an activity score, were used to assess microvascular injury and inflammatory burden.
RESULTS: Among 458 kidney transplant recipients, 93 (20%) developed AMR, of whom only 24% had detectable DSA. DSA-positive patients showed distinct clinical and histological features, including more severe microvascular inflammation and a higher frequency of concomitant T cell-mediated rejection. A high proportion of cases were classified within the severe AMR/MVI category, and activity scores were significantly higher in DSA-positive patients compared with international cohorts. Graft survival was significantly reduced in patients with AMR, with no significant differences between DSA-positive and DSA-negative cases.
CONCLUSIONS: In this single-center cohort, most AMR episodes occurred without detectable DSA. The predominance of high AMR/MVI scores suggests that patients present with later-stage histological injury at diagnosis. The use of AMR/MVI scores enabled comparison with international cohorts. These findings highlight the need for earlier diagnosis of AMR and regional limitations in comprehensive DSA assessment in Latin America.
METHODS: We conducted a retrospective analysis of kidney transplant recipients at a single center in Uruguay between 2018 and 2024. Patients with for-cause biopsies fulfilling contemporary Banff criteria for active AMR were included; chronic active AMR and non-immunologic lesions were excluded. Donor-specific antibodies were assessed at the time of biopsy using class I and II screening assays. Clinical, histological, and outcome data were compared between DSA-positive and DSA-negative AMR. Quantitative histological analyses, including an AMR/MVI index and an activity score, were used to assess microvascular injury and inflammatory burden.
RESULTS: Among 458 kidney transplant recipients, 93 (20%) developed AMR, of whom only 24% had detectable DSA. DSA-positive patients showed distinct clinical and histological features, including more severe microvascular inflammation and a higher frequency of concomitant T cell-mediated rejection. A high proportion of cases were classified within the severe AMR/MVI category, and activity scores were significantly higher in DSA-positive patients compared with international cohorts. Graft survival was significantly reduced in patients with AMR, with no significant differences between DSA-positive and DSA-negative cases.
CONCLUSIONS: In this single-center cohort, most AMR episodes occurred without detectable DSA. The predominance of high AMR/MVI scores suggests that patients present with later-stage histological injury at diagnosis. The use of AMR/MVI scores enabled comparison with international cohorts. These findings highlight the need for earlier diagnosis of AMR and regional limitations in comprehensive DSA assessment in Latin America.