Graft-versus-host disease

Graft-versus-host disease (GvHD) is a medical complication following the receipt of transplanted tissue from a genetically different person. GvHD is commonly associated with stem cell transplants such as those that occur with bone marrow transplants. GvHD also applies to other forms of transplanted tissues such as solid organ transplants. Graft-versus-host disease (GvHD) is a medical complication following the receipt of transplanted tissue from a genetically different person. GvHD is commonly associated with stem cell transplants such as those that occur with bone marrow transplants. GvHD also applies to other forms of transplanted tissues such as solid organ transplants. White blood cells of the donor's immune system which remain within the donated tissue (the graft) recognize the recipient (the host) as foreign (non-self). The white blood cells present within the transplanted tissue then attack the recipient's body's cells, which leads to GvHD. This should not be confused with a transplant rejection, which occurs when the immune system of the transplant recipient rejects the transplanted tissue; GvHD occurs when the donor's immune system's white blood cells reject the recipient. The underlying principle (alloimmunity) is the same, but the details and course may differ. GvHD can also occur after a blood transfusion if the blood products used have not been irradiated or treated with an approved pathogen reduction system. In the classical sense, acute graft-versus-host-disease is characterized by selective damage to the liver, skin (rash), mucosa, and the gastrointestinal tract. Newer research indicates that other graft-versus-host-disease target organs include the immune system (the hematopoietic system, e.g., the bone marrow and the thymus) itself, and the lungs in the form of immune-mediated pneumonitis. Biomarkers can be used to identify specific causes of GvHD, such as elafin in the skin. Chronic graft-versus-host-disease also attacks the above organs, but over its long-term course can also cause damage to the connective tissue and exocrine glands . Acute GvHD of the GI tract can result in severe intestinal inflammation, sloughing of the mucosal membrane, severe diarrhea, abdominal pain, nausea, and vomiting. This is typically diagnosed via intestinal biopsy. Liver GvHD is measured by the bilirubin level in acute patients. Skin GvHD results in a diffuse red maculopapular rash, sometimes in a lacy pattern. Mucosal damage to the vagina can result in severe pain and scarring, and appears in both acute and chronic GvHD. This can result in an inability to have sexual intercourse. Acute GvHD is staged as follows: overall grade (skin-liver-gut) with each organ staged individually from a low of 1 to a high of 4. Patients with grade IV GvHD usually have a poor prognosis. If the GvHD is severe and requires intense immunosuppression involving steroids and additional agents to get under control, the patient may develop severe infections as a result of the immunosuppression and may die of infection. However, a 2016 study found that the prognosis for patients with grade IV GvHD has improved in recent years. In the oral cavity, chronic graft-versus-host-disease manifests as lichen planus with a higher risk of malignant transformation to oral squamous cell carcinoma in comparison to the classical oral lichen planus. Graft-versus-host-disease-associated oral cancer may have more aggressive behavior with poorer prognosis, when compared to oral cancer in non-hematopoietic stem cell transplantation patients. In the clinical setting, graft-versus-host-disease is divided into acute and chronic forms, and scored or graded on the basis of the tissue affected and the severity of the reaction. Three criteria, known as the Billingham criteria, must be met in order for GvHD to occur.