Final answer:
Graft-versus-Host Disease (GVHD) occurs when a donor's transplanted immune system, such as in bone marrow transplants, recognizes the recipient's tissues as foreign and attacks them. Symptoms can include rashes, and liver and mucosa damage. To reduce GVHD risk, mature T cells may be removed from the bone marrow before transplantation.
Step-by-step explanation:
Understanding Graft-versus-Host Disease (GVHD)
Graft-versus-Host Disease (GVHD) is a specific type of transplantation complication that primarily occurs during bone marrow transplants and peripheral blood stem cell transplants. GVHD manifests in a unique way because the transplanted immune cells, particularly antigen-presenting cells (APCs) and mature T cells from the donor, can recognize the recipient's body as foreign. This recognition triggers an immune response where the donor's immune cells attack the recipient's tissue. This can lead to various symptoms such as rashes and damage to organs like the liver and the mucosa.
Bone marrow transplants are often used to treat diseases such as Severe Combined Immunodeficiency (SCID) and leukemia. In these cases, genetic differences between the donor's and recipient's tissues, particularly in the MHC (HLA) genes, often necessitate the use of immunosuppressive therapy to avoid rejection. Despite close genetic matching, transplant recipients must take these drugs to prevent their immune system from fighting off the donated tissue, leading to complications such as GVHD, infections, or cancer.
To mitigate the risks of GVHD, medical professionals may remove mature T cells from the donor bone marrow prior to transplantation. This helps to reduce the likelihood of the donor's immune cells from attacking the recipient post-transplant. Despite these precautions, graft-versus-host disease remains a significant risk and area of concern in transplant medicine.
GVHD is a complication that why it particularly occurs in bone marrow transplants is due to the presence of functional immune cells in the graft, which perceive the recipient's tissues as foreign, initiating an aggressive immune response.