(446) - Metabolic Profile of Broncho-Alveolar Lavage Fluid in Lung Transplant Recipients Suggests Potential Early Biomarkers of Bronchiolitis Obliterans Syndrome

Abstract

Purpose: The definition of antibody-mediated rejection (AMR) after lung transplantation (LT) has undergone revision as recognition of this entity has increased. Although considered a key criterion for the diagnosis of AMR, C4d deposition has been an inconsistent finding. We compared outcomes of LT recipients who developed C4d-negative AMR to those who developed C4d-positive AMR. Methods: We performed a retrospective cohort study of patients transplanted between 1/2006 and 7/2015, and identified those who developed AMR defined as acute allograft dysfunction, DSA, and a lung injury pathology. We excluded those who did not have C4d staining at the time of diagnosis (n= 20). We grouped those who developed AMR into a C4d-positive cohort and a C4d-negative cohort and compared outcomes of the 2 groups using Kaplan-Meier method and the log rank test. Results: 37 patients developed AMR during the study period; 15 developed C4d-positive AMR and 22 developed C4d-negative AMR. All patients with AMR were treated with IVIG. Of these, 36 were treated with rituximab, 7 with bortezomib, and 9 with plasma exchange (PLEX) (Table 1). Survival and CLAD-free survival after the diagnosis of AMR were poor in both groups, and there was no significant difference in either survival or CLAD-free survival between the 2 groups (Figure 1). Conclusion: A large proportion of patients with AMR in this cohort did not have C4d deposition. However, there was no significant difference in outcome between those who had C4d-negative and those who had C4d-positive AMR. These findings suggest that C4d deposition may not be a necessary criterion for the diagnosis of AMR.