An allograft or allogeneic transplant or homograft is a transplant in which transplanted cells, tissues, or organs are sourced from a genetically non-identical member of the same species. Most human tissue and organ transplants are allografts.

In contrast, a transplant from another species is called a xenograft. When a transplanted organ or tissue from a genetically identical donor, i.e., an identical twin, is termed an isograft. Finally, when a tissue is transplanted from one site to another on the same patient, it is termed an autograft.

Allografts and xenografts will be recognised by the recipient's immune system as foreign and will therefore be attacked in a process termed rejection. This does not occur in autografts or true isografts, although in practice, transplants between identical twins are usually covered with immunosuppressants in case they are not 100% genetically identical.

Tissue allografts

A variety of tissue and organs types can be used for allografts. These include:

• skin transplants
• corneal transplants
• heart transplants
• liver transplants
• kidney transplants
• bone marrow transplants
• bone allograft
• ligament or tendon allograft

See also

• Allograft diseases
• Medical grafting