Allogenic

Allogenic, also written allogeneic, is an adjective used to describe biological material or responses that originate from a genetically different individual of the same species. It is often contrasted with autologous (from the same individual) and xenogeneic (from different species) sources. The term is commonly applied in medicine, immunology, genetics, and related fields.

In transplantation medicine, allogeneic transplantation uses donor tissue or cells from another person. Examples include allogeneic bone marrow or stem cell transplants and most organ transplants. Because the donor and recipient are genetically different, the recipient’s immune system may recognize the donor tissue as foreign, potentially leading rejection or graft-versus-host disease in hematopoietic stem cell transplants. Matching of human leukocyte antigen (HLA) genes and the use of immunosuppressive therapy reduce these risks but do not eliminate them.

In immunology, allorecognition refers to the immune system’s ability to respond to non-self antigens from another individual of the same species. Alloreactive responses underlie graft rejection and are a central concern in transplantation research and practice.

In genetics and biomedical research, allogeneic materials can include cells, tissues, or cell lines derived from a donor with a different genetic background than the recipient or experimental subject. Allogeneic models help study immune responses, transplantation tolerance, and compatibility.

In geology and geomorphology, allogenic processes describe external forces, such as wind, water, and ice, that shape landscapes, as opposed to autogenic processes driven by internal rearrangements within the system.