A necessary condition for performing allogeneic transplantation is the selection of a suitable donor who has the same set of antigens as the patient. The search for a suitable donor is primarily conducted among close relatives. The chance of finding an HLA-identical relative (with matching all HLA antigens) is 1:4. If a donor is not found among relatives, a search is conducted in the appropriate bank. The transplant in this case is bone marrow or peripheral blood stem cells. In some cases, umbilical cord blood is used. The patient is prepared for transplantation using high doses of alkylating agents and radiation. This achieves the destruction of tumor cells and suppression of immunity, which is important for preventing rejection of the transplanted material.
Indications for Transplantation
Transplantation for malignant tumors can be performed after the removal of the majority of cancer cells, which is done through chemotherapy. Bone marrow transplantation is performed in cases of myeloleukemia and lymphoblastic leukemia. Such surgery is indicated for these diseases due to the risk of recurrence. Transplantation is performed in aplastic anemia, immunodeficiency, and thalassemia. The effectiveness of allogeneic transplantation in the presence of large tumors has not been fully determined.
Complications
Complications are primarily associated with the destructive effects of high doses of chemotherapy and radiation therapy on various organs. Possible damages include mucosal injury in the stomach and diarrhea. A life-threatening complication is damage to the hepatic veins, leading to liver failure. Some patients may experience interstitial pneumonia. A serious complication is infertility, affecting both men and women. The disease known as graft-versus-host disease can lead to severe illness and even death, where T-lymphocytes from the transplant attack various tissues of the host's body. This can affect the liver and intestines. Side effects may include dryness of mucous membranes and connective tissues. To prevent graft-versus-host disease, immunosuppressive therapy is conducted using cyclosporine, sometimes in combination with methotrexate, tacrolimus, and corticosteroids.