Well, this is something interesting:
An Australian girl spontaneously changed blood groups and adopted her donor’s immune system after a liver transplant, in what doctors treating her said Thursday was the first known case of its type.
Australian girl switched blood type after transplant: doctors
Demi-Lee Brennan was aged nine and seriously ill with liver failure when she received the transplant, doctors at a top Sydney children’s hospital told AFP.
Nine months later they discovered she had changed blood types and that her immune system had switched over to that of the donor after stem cells from the new liver migrated to her bone marrow.
She is now a healthy 15-year-old, Michael Stormon, a hepatologist treating her, told AFP. He said he had given several presentations on the case around the world and had heard of none like it.
“It is extremely unusual — in fact we don’t know of any other instance in which this happened,” Stormon told AFP from the Children’s Hospital at Westmead.