Alloreactivity

Alloreactivity refers to the immune system’s response to cells or tissues from another individual of the same species, such as in organ transplants. The immune system recognizes the donor’s tissue as foreign because of differences in surface molecules called human leukocyte antigens (HLAs). This recognition can trigger an immune response, leading to rejection of the transplant. While it is a natural and protective process against infections, in transplantation, alloreactivity can cause complications, requiring strategies like immunosuppressive drugs to prevent the immune system from attacking the new tissue.