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Donor DNA can be detected in recipient tissues during rejection of allograft
W L Olszewski1, M Durlik, B Lukomska
1Department of Surgical Research and Transplantation, Medical Research Centre, Polish Academy of Sciences, and Institute of Transplantology, Warsaw.
Abstract:
The main source of donor DNA in recipients of allograft are "passenger" cells. It is claimed that they are responsible for the posttransplantation microchimerism and prolongation of allograft survival. We have observed that besides cellular microchimerism, donor DNA can be found in the recipient tissues at the time of rejection of the allograft. In this study, we provide evidence for the presence in the recipient of both DNA in "passenger cells" and free DNA in tissues at the terminal stage of rejection. Male BN (RT1 n) rat heart or skin was transplanted to female LEW (RT1 l) rats followed by a vascularized bone marrow in a hindlimb transplant. In another group, heart and skin were transplanted followed by immediate i.v. infusion of donor-type bone marrow cells. CsA was given in a dose of 17 mg/kg body weight for 30 days, then the rats were followed up until day 100 unless rejection occurred earlier. LEW blood, spleen, mesenteric node and bone marrow cells were stained with moAb OX27 specific for BN but not LEW. Genomic male DNA was isolated and amplified with SRY oligonucleotide. At day 30 and day 100 cellular microchimerism was detected in blood, spleen, nodes and bone marrow cells. Donor DNA was detected in recipient skin, liver and heart extracts, as well as lymphoid organs, at the time of rejection of allograft, but not when the rats were maintained on CsA. Taken together, donor DNAwas detected in recipient tissues at the time of heart or skin rejection. It appeared to be released from cells of rejecting grafts and not from "passenger" cells, representing only a minor cellular mass compared with the graft.
Insights
Donor DNA in transplant recipients can originate from "passenger" cells or be released from rejecting grafts. This study found free donor DNA in recipient tissues during allograft rejection, distinct from passenger cell DNA.
Area of Science:
- Transplantation immunology
- Molecular biology
- Genetics
Background:
- Donor DNA in allograft recipients is primarily attributed to "passenger" cells, believed to cause microchimerism and prolong graft survival.
- Previous observations suggest donor DNA presence in recipient tissues during allograft rejection, beyond cellular microchimerism.
Purpose of the Study:
- To investigate the presence and origin of donor DNA in recipient tissues during allograft rejection.
- To differentiate between donor DNA from "passenger" cells and DNA released from the rejecting graft.
Main Methods:
- Rat models (BN to LEW) involving heart, skin, and bone marrow transplantation.
- Cyclosporine A (CsA) immunosuppression was administered.
- Detection of donor DNA using SRY oligonucleotide amplification in recipient blood, spleen, lymph nodes, bone marrow, skin, liver, and heart.
Main Results:
- Cellular microchimerism was consistently detected in recipient immune cells.
- Free donor DNA was identified in recipient tissues (skin, liver, lymphoid organs) specifically during allograft rejection.
- Donor DNA was absent in tissues when rats were maintained on CsA, indicating a link to the rejection process.
Conclusions:
- Donor DNA in recipient tissues during allograft rejection originates from the rejecting graft itself, not solely from "passenger" cells.
- This free donor DNA represents a significant component released from graft cells during rejection.
- Findings challenge the exclusive role of "passenger" cells in explaining allograft rejection-associated donor DNA presence.