Final answer:
Gamma irradiation of cellular blood components is necessary to prevent graft-versus-host disease (GVHD) by inactivating donor lymphocytes, which could otherwise attack the recipient's body after a bone marrow transplant or peripheral blood stem cell transplant.
Step-by-step explanation:
In the context of blood transfusions and bone marrow transplants, gamma irradiation of cellular blood components is required to prevent graft-versus-host disease (GVHD). This is a complication that can occur when the immune cells in the donated blood components recognize the recipient's body as foreign and mount an immune response, which can be detrimental to the recipient. Gamma irradiation prevents this by inactivating the donor's lymphocytes, making them unable to proliferate and causing GVHD.
GVHD primarily occurs in recipients of bone marrow transplants and peripheral blood stem cells. To mitigate the risk of GVHD, one strategy utilized is the removal of mature T cells from donor bone marrow before transplantation. However, gamma irradiation of donated blood products is another critical step to ensure that any residual T cells are rendered inactive.