Final answer:
Organ transplants carry a risk of rejection due to differences in MHC proteins between donor and recipient, with blood relatives being preferred donors to decrease rejection risk, and immunosuppression being key to prevent organ rejection.
Step-by-step explanation:
Organ transplants are considered dangerous for several reasons, one of which is the risk of organ rejection. When an organ from an incompatible donor is transplanted to a recipient, the recipient's immune system will recognize the donor's MHC (Major Histocompatibility Complex) proteins as foreign. This is because different MHC class I molecules between donor and recipient can cause the immune system to attack the transplanted organ, leading to rejection. Blood relatives are often preferred as organ donors because the genetic similarities can reduce the likelihood of rejection. To mitigate the immune response, immunosuppressive therapy is used, which is a critical component in transplantation procedures.