Final answer:
Common locations for graft obstructions would depend on the type of graft; in bone marrow transplants, it historically occurred near the iliac crest, while in organ transplants it could be at surgical connection sites. Graft rejection, involving immune response markers such as MHC I and MHC II, also plays a role in graft complications.
Step-by-step explanation:
The common locations for graft obstructions can vary depending on the type of graft. For example, in the context of bone marrow transplants, a historical practice involved the insertion of a large-bore needle into the area near the iliac crest of the pelvic bones. This area was chosen due to its accessibility and distance from vital organs, despite the procedure being notably painful. However, in the context of organ transplantation, common locations for obstructions will differ. For instance, coronary artery bypass grafts may be obstructed in the coronary arteries, vascular grafts in the leg arteries could develop obstructions due to plaque build-up, and other organ transplants might face issues at the site of surgical connection to the recipient's blood vessels. Graft rejection is a significant risk associated with transplantation. The immune system may recognize the donor tissue as foreign (non-self) through the major histocompatibility complex markers MHC I and MHC II, leading to an immune response that can result in graft failure. The type of graph also impacts rejection risks, with autografts typically presenting the lowest rejection rates and xenografts the highest.