What will happen if a person with AB-negative blood receives a blood transfusion from someone with O-positive blood?
I. Nothing; AB blood is the “universal recipient” and can receive any blood type without eliciting an immune response.
II. Nothing; O-positive blood is the “universal donor”, meaning that any blood type can receive it without eliciting an immune response.
III. The recipient will experience an immune response against the Rh antigen.
IV. The recipient will experience an immune response against the O antigen.
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Correct Answer: C. III only
This question is a little tricky. A person with AB blood is the universal recipient ONLY if they contain ALL antigens — this includes the Rh antigen (aka if they are “positive”). In other words, a person with AB-negative blood will have antibodies against the Rh antigen (against any “positive” blood type). Additionally, universal donor blood must contain NO antigens, meaning it must not contain A, B or Rh antigens. While O blood is the “universal donor”, this is ONLY true if the blood is negative (void of the Rh antigen). While O-positive blood can be accepted by A-positive, B-positive, and AB-positive, it will trigger an immune response in someone with negative blood, because their blood would contain antibodies against the Rh factor.
Thus, because the recipient blood is negative (does not contain Rh antigens), it therefore contains antibodies (and will elicit immune response) against the Rh factor of someone with O-positive blood. This leaves us with answer choice C.
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