Donor Extracellular Vesicles Trigger B-cell Allorecognition in Transplantation

Presenter: Dr. Adrian Morelli, Starzl Transplant Institute

The idea that donor-derived passenger leukocytes (i.e. dendritic cells) transplanted with the grafts and mobilized to lymphoid tissues are essential for presentation of donor MHC molecules to allo-reactive naïve T cells in graft-draining secondary lymphoid tissues has been recently challenged. Recent evidence indicates that allografts also release donor-derived small extracellular vesicles (EVs) (i.e. exosomes) that carry on its surface the donor antigen. Once the donor-derived EVs arrive in the graft-draining secondary lymphoid tissues, the EVs are presented not only to allo-reactive T cells, as recently demonstrated, but also to donor-reactive B lymphocytes that recognize the donor MHC molecules on the vesicle surface. The present talk will be focused on the latter mechanism.

Relevant Publications

• Donor dendritic cell–derived exosomes promote allograft targeting immune response
• Extracellular vesicle-mediated MHC cross-dressing in immune homeostasis, transplantation, infectious diseases, and cancer