What explains a positive DAT in a case of transfusion reaction involving anti-Jkb?

A positive Direct Antiglobulin Test (DAT) in the context of a transfusion reaction suggests that there are antibody-coated red blood cells present. In the case involving anti-Jkb, the correct interpretation is that the donor cells were likely positive for the Jkb antigen.

When a recipient who does not have anti-Jkb antibodies receives red blood cells from a donor with the Jkb antigen, the recipient’s immune system may recognize this foreign antigen as a target. If the recipient already has anti-Jkb antibodies from previous sensitization (such as pregnancy or prior transfusions), these antibodies will bind to the Jkb antigen on the transfused red blood cells, leading to agglutination and hemolysis. The DAT will subsequently show a positive result because it detects these antibodies bound to the donor red blood cells.

The other options do not adequately explain the positive DAT in this scenario. The donor cells having a positive DAT does not account for the transfusion reaction since the focus is on the recipient's immune response. Polyagglutinability refers to a situation where blood group antigens are altered or obscured, which is not relevant in the case of a straightforward reaction to Jkb. Lastly, while it's theoretically possible for the recipient cells