A patient develops generalized itching during a packed red blood cell transfusion with stable vital signs. The most likely underlying mechanism is a mild allergic reaction. Which option best reflects the antibody involved?

A patient develops generalized itching during a packed red blood cell transfusion with stable vital signs. The most likely underlying mechanism is a mild allergic reaction. Which option best reflects the antibody involved?

• A. Rh
• B. ABO
• C. MN, P & Lewis
• D. None of the above

Answer: (D)

Mild allergic (urticarial) transfusion reactions are caused by the recipient’s IgE antibodies reacting to donor plasma proteins, leading to histamine release. This mechanism is separate from antibodies directed at red cell antigens. ABO and Rh antibodies target red blood cell antigens and are associated with hemolytic or febrile transfusion reactions, not isolated itching with stable vital signs. MN, P, and Lewis are also red cell antigens, so antibodies against them don’t explain a simple allergic reaction to transfused plasma. Therefore, none of the listed antibody specificities fits this scenario. The actual mechanism would be IgE against donor plasma proteins (or anti-IgA in IgA deficiency), which are not among the options.

Mild allergic (urticarial) transfusion reactions are caused by the recipient’s IgE antibodies reacting to donor plasma proteins, leading to histamine release. This mechanism is separate from antibodies directed at red cell antigens. ABO and Rh antibodies target red blood cell antigens and are associated with hemolytic or febrile transfusion reactions, not isolated itching with stable vital signs. MN, P, and Lewis are also red cell antigens, so antibodies against them don’t explain a simple allergic reaction to transfused plasma. Therefore, none of the listed antibody specificities fits this scenario. The actual mechanism would be IgE against donor plasma proteins (or anti-IgA in IgA deficiency), which are not among the options.