Question:medium
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
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Recall what the Donath-Landsteiner (D-L) test detects. It is a cold-warm biphasic hemolysin of the IgG class, and finding it confirms paroxysmal cold hemoglobinuria.
Step 2: Mechanism - the IgG attaches to the P blood-group antigen on erythrocytes at low temperature, then on warming to body temperature it triggers the full complement cascade, ending in massive intravascular hemolysis with hemoglobin spilling into the urine.
Step 3: Clinical associations include syphilis as well as viral and atypical infections such as mycoplasma, mumps, measles and influenza-like illness, which is why a cold-induced hemoglobinuria after infection points to PCH.
Step 4: Eliminate distractors - PNH lacks GPI-anchored complement inhibitors (no antibody), Waldenstrom secretes IgM, and malaria lyses cells through intra-erythrocytic parasites.
\[\boxed{\text{Paroxysmal cold hemoglobinuria}}\]
Step 2: Mechanism - the IgG attaches to the P blood-group antigen on erythrocytes at low temperature, then on warming to body temperature it triggers the full complement cascade, ending in massive intravascular hemolysis with hemoglobin spilling into the urine.
Step 3: Clinical associations include syphilis as well as viral and atypical infections such as mycoplasma, mumps, measles and influenza-like illness, which is why a cold-induced hemoglobinuria after infection points to PCH.
Step 4: Eliminate distractors - PNH lacks GPI-anchored complement inhibitors (no antibody), Waldenstrom secretes IgM, and malaria lyses cells through intra-erythrocytic parasites.
\[\boxed{\text{Paroxysmal cold hemoglobinuria}}\]
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