In a patient with warm autoimmune hemolytic anemia, the direct antiglobulin test at 37°C is positive. Which autoantibody class is most likely responsible?

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Multiple Choice

In a patient with warm autoimmune hemolytic anemia, the direct antiglobulin test at 37°C is positive. Which autoantibody class is most likely responsible?

Warm autoimmune hemolytic anemia is driven by autoantibodies that react with red blood cells at body temperature. The direct antiglobulin test at 37°C detects antibodies bound to the surface of RBCs, and in warm AIHA the primary antibody class is IgG. IgG-coated RBCs are what the DAT picks up, often with some complement deposition as a secondary event. IgM, which reacts best at cooler temperatures, is the typical driver in cold agglutinin disease and usually involves complement more than IgG binding at 37°C. IgA is not a common player in AIHA. So the most likely responsible autoantibody class is IgG.

Warm autoimmune hemolytic anemia is driven by autoantibodies that react with red blood cells at body temperature. The direct antiglobulin test at 37°C detects antibodies bound to the surface of RBCs, and in warm AIHA the primary antibody class is IgG. IgG-coated RBCs are what the DAT picks up, often with some complement deposition as a secondary event. IgM, which reacts best at cooler temperatures, is the typical driver in cold agglutinin disease and usually involves complement more than IgG binding at 37°C. IgA is not a common player in AIHA. So the most likely responsible autoantibody class is IgG.

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