DNA transfer in bacteria and animals (humans).

Transplanted vascularized organs shed passenger cells, normal constituents of whole organs, that migrate to recipient lymphoid tissues and produce microchimerism. These cells lysed by recipient cytotoxic cells release cellular organelles into the recipient circulation. In addition, warm and cold ischemia as well as immune rejection of the transplanted organ or tissue bring about destructive changes in the graft parenchymatous cells. Fragments of disintegrated cellular organelles are phagocytized by recipient scavenger cells located in lymph nodes, spleen and liver and digested. Some fragments are incorporated into dendritic cells (DC) and processed. Donor DNA is present in the ingested cellular debris. The allografting with immunosppression is accompanied by microbial infections and host reaction. A large volume of bacterial and viral DNA is shed in the recipient circulation. The fate of the shed DNA remains largely unknown. Does it undergo total disintegration or may be reutilized? What reaction may the non-methylated bacterial DNA evoke in the graft and what is the response of allogeneic recipient to donor DNA remain the unanswered questions.