A patient admitted to an intensive care unit is receiving a blood transfusion. Which of the following immunogenic deficiencies is associated with the development of an anaphylactic reaction?

1. A

   IgG deficiency

2. B

   IgM deficiency

3. C

   IgE deficiency

4. D

   IgA deficiency

Appeared in: NORCET 8 Prelims-2025

Explanation

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• Selective IgA deficiency is the primary immunodeficiency most commonly associated with anaphylactic transfusion reactions.
• Individuals with this condition may develop anti-IgA antibodies (often of the IgG or IgE class) because their immune system recognizes the foreign IgA protein.
• Upon transfusion with blood products containing IgA, these pre-formed antibodies trigger a massive mast cell degranulation, leading to a rapid and severe Type I hypersensitivity (anaphylactic) reaction.

Why Other Options Were Wrong

• Option A: IgG deficiency primarily increases susceptibility to recurrent bacterial infections due to a lack of opsonizing antibodies. It is not the cause of anaphylactic transfusion reactions.
• Option B: IgM deficiency is a rare disorder that impairs the primary immune response to infection, particularly from encapsulated bacteria. It is not linked to transfusion-related anaphylaxis.
• Option C: IgE is the antibody that mediates Type I hypersensitivity reactions. Therefore, a deficiency of IgE would theoretically decrease, not cause, the risk of an anaphylactic reaction.

Related Visual

• Visual 1: Diagram: Mechanism of Anaphylaxis in IgA Deficiency. A visual showing an IgA-deficient patient with pre-formed anti-IgA antibodies. When donor blood with IgA is introduced, the antibodies bind to the IgA and cross-link on mast cells, triggering histamine release.
• Visual 2: Infographic: Types of Transfusion Reactions. A chart comparing allergic, febrile non-hemolytic, acute hemolytic, and anaphylactic reactions, detailing their onset, key symptoms, and underlying cause.

Clinical Relevance

• Nursing practice connection: Use the key finding related to Pathophysiology of Anaphylactic Transfusion Reactions to guide bedside assessment, documentation, and the next nursing action.
• Nurses must be vigilant in monitoring for signs of an anaphylactic reaction (e.g., hypotension, wheezing, urticaria, anxiety) within the first few minutes of starting any blood transfusion.
• Immediate intervention is life-saving: stop the transfusion, maintain the IV line with normal saline, and prepare to administer epinephrine as per protocol.
• For patients with a known IgA deficiency, the nurse has a critical role in verifying that only appropriate blood products (washed cells or blood from an IgA-deficient donor) are administered to prevent a reaction.

How to Approach the Question

• First, identify the key concepts in the question: 'blood transfusion', 'anaphylactic reaction', and 'immunogenic deficiency'.
• This is a clinical knowledge question that requires recalling a specific pathophysiological link.
• Analyze the options based on the function of each immunoglobulin. IgE is the classic 'allergy' antibody, but the question asks about a deficiency that causes the reaction, which is a paradox.
• This paradox is the key to the answer. The deficiency of one component (IgA) leads the body to see it as foreign when introduced, triggering an immune attack.
• Recall that selective IgA deficiency is the classic textbook example of an immunodeficiency that predisposes to anaphylactic transfusion reactions due to the formation of anti-IgA antibodies.
• Eliminate the other options: IgG and IgM deficiencies primarily cause infections, and an IgE deficiency would reduce allergic potential.

Concept Tested & Keywords

• Concept Tested: Pathophysiology of Anaphylactic Transfusion Reactions
• Stem keywords: blood transfusion, anaphylactic reaction, immunogenic deficiency, intensive care unit
• Lead-in keywords: Which of the following
• Clinical cues: A patient receiving a blood transfusion develops an anaphylactic reaction.

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