1. The reason for the development of allergy is the presence of plasma and the process of washing helps in the removal of residual plasma. if the Patient is having a history of allergy - Antihistaminic drugs -reduce the chances of development of allergic reactions during blood transfusion. 2. Irradiation - reduces the chance of development of Graft Versus Host Disease. Irradiation - causes - reduction in the number of the immunocompetent cells (lymphocytes mainly) Irradiation of cellular blood components (red blood cells, platelets, and granulocytes) is indicated to prevent the development of transfusion-associated graft-versus-host disease (TA-GVHD). Patients at risk of TA-GVHD include immunocompromised patients who are receiving a bone marrow or stem cell transplant and fetuses undergoing an intrauterine transfusion. Irradiation is also indicated for recipients of components collected from a blood relative or HLA-matched donors. 3. Leukocyte reduction - Leukoreduction of whole blood and blood components has been shown to reduce recurrent febrile non-hemolytic transfusion reactions, reduce alloimmunization to leukocyte antigens that may complicate care of patients whoundergo transplantation or chronic transfusion therapy, and protect against transmission of cytomegalovirus (CMV) to patients at increased risk of CMV disease. antibodies in the recipient - react with donor leukocytes - release of cytokines - cause fever- known as Febrile Non-Hemolytic Transfusion Reaction. 4. Glycolisation - addition of glycol. useful in autologous blood transfusion - increases the life span of RBC. If the patient is having a history of development of anaphylaxis after blood transfusion, the patient is most likely to be suffering from IgA deficiency.