Abstract
PURPOSE OF REVIEW: Exosomes have garnered increasing interest due to their involvement in a wide array of biological processes, including immunity and regeneration. In this review, we outline our current understanding of the role of exosomes in modulating transplant immune responses and as biomarkers of allograft function or rejection. RECENT FINDINGS: The exosomal effect on post-transplant immunity is heterogeneous and context dependent. They are critical for priming anti-donor T cell immunity via semi-direct presentation but have also been shown to promote tolerance to graft-expressed non-inherited maternal antigens. Post-transplant, proteomic and gene expression profiling of exosomes collected from blood, urine, or bronchoalveolar lavage can discriminate between cellular and antibody-mediated rejection and as a potential early prognostication tool. SUMMARY: Secreted by both the donor and recipient cells after solid organ transplantation, exosomes are mechanistic mediators of the allogeneic immunity and have shown promise as non-invasive biomarkers of graft function.