Blood transfusion GvHD

Contamination of blood products with lymphocytes can lead to transfusion-induced reactions ranging from a mild fever to severe reactions such as alloimmunization and graft versus host disease (GvHD), in which the transfused lymphocytes (graft) survive the defensive immune reaction of the patient (host) and start a reaction which destroys the cells of the host. The patient also may develop an immune response to the human leukocyte antigen (HLA) type of the graft s cells and reject all platelet transfusions that do not match their own HLA system. The HLA system, found on blood platelets and lymphocytes, is more compHcated than, but similar to, the ABO blood group system of red cells. 

Filtration Filtration (qv) is appHed in blood cell separation to remove leukocytes from ted blood cell (RBC) and platelet concentrates. Centtifugational blood cell separators do not reduce white blood cells (WBC) in red cell and platelet products sufficiently to avoid clinical complications such as GvHD and alloimmunization. A post-apheresis filtration step is needed to further reduce the WBC load. Modem filters are capable of a 3-log reduction in white cell contamination of the blood product, eg, apheresis single-donor platelet units having a typical white cell contamination of 5 x 10 white cells in 4 x 10 platelets can be reduced to a 5 x 10 white cell contamination, a sufficiently low number to avoid severe transfusion reactions. 

Packed RBC transfusions are indicated to keep hemoglobin levels above 7 to 8 g/dL to maintain adequate oxygen-carrying capacity. Each unit of packed RBCs should increase the hemoglobin level by approximately 1 g/dL unless active blood loss is evident. RBCs should also be filtered to reduce the risk of nonhemolytic, febrile transfusion reactions. Patients who are candidates for bone marrow transplantation should receive blood products that have been irradiated with 2,500 cGy to prevent transfusion-associated GVHD. 

If blood or platelet transfusion are necessary for the above immunodeficiency disorders they must always be irradiated to prevent the risk of life-threatening Graft versus host disease (GVHD). 

Adverse events related to transfusion of blood components have been reported, including febrile non-hemolytic transfusion reactions, mild febrile reactions, acute and delayed hemolytic transfusion reactions, transfusion-related acute lung injury (TRALl), anaphylactic and other allergic reactions, graft-versus-host disease (GvHD), transfusion-associated circulatory overload (TACO), viral infections, post-transfusion bacteremia, transfusion-associated sepsis (TAS), hemosiderosis, post-transfusion purpura, and new allo-antibody formation [18 , 19 ]. Whole blood, erythrocytes, leukocytes, platelets, and plasma for transfusion (fresh frozen plasma, FFP) are involved. Quite a number of these adverse effects, such as TRALl, TACO, TAS, and allergic/anaphylactic reactions can be difficult to evaluate. 

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