Question:
Donath-Landsteiner antibody is seen in?
Donath-Landsteiner antibody is seen in?
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Biphasic IgG against the P-antigen, active in the cold.
Updated On: Jun 24, 2026
- PNH
- Waldenstrom's macroglobulinemia
- Paroxysmal cold hemoglobinuria
- Malaria
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The Correct Option is C
Solution and Explanation
Step 1: The Donath-Landsteiner antibody is the diagnostic marker of paroxysmal cold hemoglobinuria (PCH). It is a biphasic IgG autoantibody that binds red cells in the cold and fixes complement on rewarming.
Step 2: The antibody is directed against the P-antigen on the red cell surface. The antigen-antibody complex activates complement, generating the membrane attack complex that lyses cells directly, causing intravascular hemolysis and hemoglobinuria after cold exposure.
Step 3: Why the others are wrong - PNH is due to a PIGA mutation with deficient CD55 and CD59 (complement regulators), not an antibody. Waldenstrom macroglobulinemia produces an IgM paraprotein, not Donath-Landsteiner antibody. Malaria causes hemolysis by direct red cell parasitism, not by this autoantibody.
Answer: Paroxysmal cold hemoglobinuria.
Step 2: The antibody is directed against the P-antigen on the red cell surface. The antigen-antibody complex activates complement, generating the membrane attack complex that lyses cells directly, causing intravascular hemolysis and hemoglobinuria after cold exposure.
Step 3: Why the others are wrong - PNH is due to a PIGA mutation with deficient CD55 and CD59 (complement regulators), not an antibody. Waldenstrom macroglobulinemia produces an IgM paraprotein, not Donath-Landsteiner antibody. Malaria causes hemolysis by direct red cell parasitism, not by this autoantibody.
Answer: Paroxysmal cold hemoglobinuria.
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