Detection of Donor-Derived Microparticles in the Peripheral Blood of a Hand Transplant Recipient During Rejection

BACKGROUND Microparticles (MPs) are released from the plasma membrane of activated or dying cells and bear surface molecules from those cells. We examined whether donor-derived MPs in the peripheral blood of the recipient could serve as a marker of tissue damage due to rejection of a transplanted hand. METHODS Platelet-free plasma from the recipient of the transplanted hand was analyzed for MPs bearing the donor-specific HLA molecule A*02 using flow cytometry. Rejection status of the transplanted hand was monitored by histopathology of skin punch biopsies. RESULTS Donor-specific MPs expressing HLA A*02 were quantifiable in the peripheral blood of the recipient. Levels of these MPs increased with worsening rejection of the transplanted hand. CONCLUSIONS These findings demonstrate the ability to detect donor specific MPs through staining of graft cell-specific HLA and promote further investigation into the potential utility of flow cytometry for donor-derived MPs as a noninvasive tool to assess rejection in solid organ transplantation patients.