A patient with selective IgA deficiency who requires a blood transfusion is at risk of anaphylaxis. This reaction is mediated by:
- A Type I hypersensitivity to donor IgA mediated by patient's anti-IgA IgE antibodies ✓
- B Type II cytotoxic reaction against donor red blood cells
- C Type III immune complex deposition in the microvasculature
- D Complement-independent NK cell-mediated cytotoxicity
Correct answer: A. Type I hypersensitivity to donor IgA mediated by patient's anti-IgA IgE antibodies
Explanation
Patients with selective IgA deficiency can produce IgG and/or IgE anti-IgA antibodies. When transfused with blood products containing IgA, these anti-IgA IgE antibodies trigger mast cell degranulation causing systemic anaphylaxis. Washed red blood cells or IgA-deficient blood products should be used. This is a classic Type I hypersensitivity mechanism.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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