Spleen dendritic cells of recipients of allogeneic but not syngeneic heart grafts internalize donor DNA fragments.

Microchimerism after allogeneic organ transplantation has been widely documented using DNA identification techniques. However, the question as to whether the detected donor DNA is present in the surviving donor cells, recipient macrophages phagocytizing rejected donor cells or recipient dendritic cells internalizing donor apoptotic bodies or cell fragments has not been answered. We provide evidence that allogeneic organ transplantation is followed not only by cellular microchimerism caused by release of graft passenger cells but also dissemination of donor DNA from the rejecting graft cells and its internalization in recipient dendritic cells (DC).