A 35-year-old woman with systemic lupus erythematosus presents with fatigue, jaundice, and pallor. Peripheral smear shows spherocytes and a positive direct Coombs test. The mechanism of red blood cell destruction in this patient is best described as:
- A Type I hypersensitivity
- B Type III hypersensitivity
- C Type II hypersensitivity ✓
- D Type IV hypersensitivity
Correct answer: C. Type II hypersensitivity
Explanation
Warm autoimmune hemolytic anemia in SLE is a type II hypersensitivity reaction, where IgG autoantibodies bind red blood cell surface antigens leading to extravascular hemolysis via splenic macrophage Fc receptor-mediated destruction. Type I involves IgE and mast cells. Type III involves immune complex deposition. Type IV is T-cell mediated.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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