Cellular and Histopathological Hallmarks of Acute and Chronic Rejection in Vascular Composite Allografts: A Systematic Review.
Leonard Knoedler, Tobias Niederegger, Jakob Fenske et al.
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In 30 seconds
This systematic review synthesized human studies describing cellular, immunophenotypic, and histopathological features of acute and chronic rejection in vascular composite allografts (VCAs). Across 51 studies, 208 rejection episodes were reported: 177 (85%) were acute and 31 (15%) chronic, with distributions differing by VCA type (p < 0.0001). Acute rejection was predominantly T-cell-driven, whereas chronic rejection was characterized by endothelial involvement, graft vasculopathy, and fibrosis. The authors found heterogeneous patterns across graft types and noted limited reporting, particularly for chronic rejection.
Key findings
- Of 208 reported rejection episodes, 177 (85%) were acute and 31 (15%) chronic; distributions differed by VCA type (p < 0.0001).
- Acute rejection was mainly T-cell-driven, with CD8+ cells in 49%, CD4+ in 47%, and CD3+ in 35%.
- Chronic rejection featured endothelial involvement or graft vasculopathy (n = 10, 20%) and fibrosis (n = 6, 12%).
- Histopathology was reported in 78% of studies; cellular infiltrates were reported in 73% and perivascular lymphocytic infiltrates in 71%.
Why it matters
Acute and chronic rejection show different, graft-type-dependent immune and tissue injury patterns. Recognizing these distinctions may help frame VCA surveillance and interpretation of biopsy findings. The review also highlights that the evidence base is heterogeneous and chronic rejection is less well documented, limiting confidence in consistent diagnostic approaches.
What to keep in mind
Heterogeneity in the included studies precluded meta-analysis, and reported data were limited, especially for chronic rejection.