Define "transplantation immunology."

Transplantation immunology focuses primarily on the immune response to transplanted tissues and organs. This field of study is critical because, upon transplantation, the recipient's immune system can recognize the transplanted tissue as foreign, leading to rejection. Understanding how the immune system interacts with the graft is essential for developing strategies to prevent rejection and enhance acceptance of the transplant. This involves studying both the cellular and humoral immune responses that can affect transplant success.

The other concepts mentioned, while related to transplantation, do not encapsulate the essence of transplantation immunology. Improving surgical techniques, donor selection criteria, and analyzing long-term outcomes are significant aspects of transplantation as a whole but do not specifically address the immune mechanisms at play, which is the core of transplantation immunology. The immune response is vital in ensuring the longevity and effectiveness of transplants, making its study critical for advancing the field.