A 37-year-old woman received two units of packed red blood cells following a surgical procedure.She had been transfused once before.Five days after surgery,she experienced a slight fever and some hemoglobin in her urine,indicating a delayed transfusion reaction.A direct antiglobulin test on a blood sample was positive.Which of the following statements best describes this reaction?

Question

Quizplus · Accepted Answer

A positive direct antiglobulin test (DAT) indicates that antibodies are bound to the patient's red blood cells. In this case, the reaction was delayed and the patient had received blood before, suggesting an amnestic response. An amnestic response occurs when a person is exposed to an antigen, develops an immune response, and then is exposed to the same antigen later. The second exposure triggers a faster and stronger response, often resulting in a delayed transfusion reaction. Option A is incorrect because IgM antibodies would have resulted in a positive DAT at immediate spin, rather than a delayed reaction. Option C is incorrect because IgE is not typically involved in transfusion reactions. Option D is incorrect because the reaction was delayed, and in most delayed transfusion reactions, the antibody present reacts best at 37°C, rather than room temperature.

A 37-Year-Old Woman Received Two Units of Packed Red Blood