What considerations are necessary regarding immune response during blood transfusion?

From the Guidelines

When considering immune reactions during blood transfusions, it is crucial to adopt a personalized approach, tailored to the patient's symptoms and signs, to distinguish between febrile and allergic reactions, as recommended by current guidelines from SHOT 1. This approach is essential to ensure the safe administration of blood components and minimize the risk of adverse reactions.

• Febrile reactions are typically associated with red blood cell units, and treatment may only require intravenous paracetamol.
• Allergic reactions, more commonly caused by plasma and platelets, should be managed with antihistamines.
• In cases of severe reactions or anaphylaxis, local anaphylaxis protocols should be followed. The incidence of febrile, allergic, and hypotensive reactions following transfusion is increasing 1, highlighting the need for close monitoring of patients and careful consideration of transfusion requirements.
• Patients should be assessed for the need for transfusion, and body weight dosing of RBCs should be used, along with slow transfusion and close monitoring of vital signs and fluid balance.
• Prophylactic diuretic prescribing may also be necessary, and various infographics and TACO checklists are available from SHOT to guide clinical decision-making 1. It is also important to note that steroids and antihistamines should not be used indiscriminately, as repeated doses of steroids may further suppress immunity in immunocompromised patients 1.

From the Research

Immune Reaction Considerations

When considering immune reactions during blood transfusion, several factors come into play.

• The majority of reactions that occur during blood transfusion are stimulated when the recipient receives antigen from donor blood to which they have developed antibody 2.
• Symptoms of a reaction can range from mild discomfort to death, and it is critical to stop the transfusion immediately and report the reaction to the blood bank if a reaction is suspected 3.
• Most adverse blood transfusion events are immune-mediated, and in the majority of severe reactions, antibodies can be identified as causal factors 4.
• Alloimmunization can cause symptomatic reactions, and transfused cells can also be silently destroyed, contributing to hemolytic disease of the newborn and allograft rejection after transplantation 4.

Prevention and Management

To prevent and manage immune reactions, the following should be considered:

• New evidence-based algorithms of transfusion, newer blood screening methods, and donor policies and deferrals can lead to the avoidance of unnecessary transfusions and decrease the incidence of serious transfusion reactions 3.
• Extended matching can help reduce alloimmunization, particularly against red blood cells, as a cause of severe hemolytic transfusion reactions 4.
• The use of acetaminophen and diphenhydramine premedication before blood component transfusions has been questioned, as they have failed to prevent transfusion reactions and may have potential toxicity 5.
• Leukoreduction of cellular blood products can reduce the incidence of immunological platelet transfusion refractoriness, and the avoidance of plasma- and platelet-products from females can decrease transfusion-related acute lung injury (TRALI) 4.

Immune Effects of Blood Transfusion

The immune effects of blood transfusion are complex and can include:

• Stimulation and modulation of the immune system 6.
• Tolerance and suppression of the immune system 6.
• Induction of cell anergy and apoptosis 6.
• The release of soluble molecules, such as HLA class I and II and Fas ligand molecules, which can have immunomodulating effects 6.