• Related allogeneic donors, usually sibling donors
Both related and unrelated allogeneic transplantation differs from either syngeneic or autologous transplantation in that the following may occur:
"The tissue type of an individual is determined by proteins on the surface of cells.
• Host versus graft effect (the patient’s cells reject the transplanted donor marrow or blood stem cells), or
• Graft versus host disease (the transplanted donor immune cells attack the patient’s body).
"However, the fact that these reactions do happen in nonidentical siblings, even if they are matched by tissue typing, shows that HLA testing does not examine all relevant tissue type factors. In light of this fact, two processes are necessary to permit a successful transplant: suppression of the recipient’s immune system before transplant and suppression of the donor’s immune cells in the recipient after transplant."Reference:"Blood and Marrow Stem Cell Transplantation"The Leukemia & Lymphoma Society