Antiperlecan Antibodies Are Novel Accelerators of Immune‐Mediated Vascular Injury

Acute vascular rejection (AVR) is characterized by immune‐mediated vascular injury and heightened endothelial cell (EC) apoptosis. We reported previously that apoptotic ECs release a bioactive C‐terminal fragment of perlecan referred to as LG3. Here, we tested the possibility that LG3 behaves as a neoantigen, fuelling the production of anti‐LG3 antibodies of potential importance in regulating allograft vascular injury. We performed a case–control study in which we compared anti‐LG3 IgG titers in kidney transplant recipients with AVR (n = 15) versus those with acute tubulo‐interstitial rejection (ATIR) (n = 15) or stable graft function (n = 30). Patients who experienced AVR had elevated anti‐LG3 titers pre and posttransplantation compared to subjects with ATIR or stable graft function (p