What does the term 'mismatched transplant' refer to?

The term 'mismatched transplant' specifically pertains to a transplant procedure where the donor and recipient possess some differences in their Human Leukocyte Antigen (HLA) types. In the context of transplantation, HLA molecules play a crucial role in the body's immune response by presenting antigens to T cells. When a donor's HLA types are not identical to those of the recipient, the immune system may recognize the transplanted tissue as foreign, leading to a potential graft rejection.

In many cases of mismatched transplants, particularly in the presence of significant HLA differences, the recipient's immune system may mount a response against the transplant, making it critical to manage the risk of rejection through immunosuppressive therapy. Hence, the term emphasizes the relevance of HLA compatibility in transplant success and highlights the complexities involved in transplant immunology where mismatches can affect patient outcomes.