Graft-versus-host disease

Graft-versus-host disease is tissue injury caused when immune cells from a donor attack a transplant recipient. It occurs most often after allogeneic hematopoietic cell transplantation and can be acute or chronic.

Alloreactivity: An immune response directed against genetically different cells from another individual. Donor immune cells recognize recipient molecules as foreign, initiating the attack.
Allogeneic hematopoietic cell transplantation: A treatment that replaces a patient's blood-forming cells with cells from another person. This transplant is the setting in which graft-versus-host disease most commonly arises.
Graft-versus-tumor effect: The ability of donor immune cells to recognize and destroy malignant cells after transplantation. It is a beneficial donor immune response that can occur alongside harmful tissue attack.
Graft-versus-leukemia effect: The immune-mediated destruction of leukemia cells by donor cells after allogeneic transplantation. The same donor immunity that injures recipient tissues may help control the underlying malignancy.
Human leukocyte antigen: Highly variable cell-surface proteins that present peptides to T cells and help distinguish self from nonself. Differences between donor and recipient HLA molecules strongly influence recognition and disease risk.
HLA matching: The comparison of donor and recipient HLA types to assess compatibility before transplantation. Closer matching can reduce, but does not eliminate, the risk of disease.
Host-versus-graft disease: Immune rejection in which the recipient's immune system attacks transplanted donor cells or tissue. The direction of attack is reversed: recipient immunity targets the graft rather than donor cells targeting the recipient.
Skin manifestations of graft-versus-host disease: Skin changes caused by graft-versus-host disease, ranging from rashes to sclerosis and contractures. The skin is a frequent target and can show both early inflammation and chronic scarring.
T cell: A lymphocyte that recognizes specific antigens and coordinates or carries out adaptive immune responses. Donor T cells are central effectors that recognize recipient antigens and injure tissues.
Calcineurin inhibitor: A drug that suppresses T-cell activation by blocking calcineurin-dependent signaling. Drugs such as cyclosporine and tacrolimus are used to prevent or treat donor T-cell responses.

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