A patient with an anti-HLA-A2 antibody would likely have a PRA of?

A patient with an anti-HLA-A2 antibody will have a panel-reactive antibody (PRA) level that reflects the proportion of the population’s HLA types that the patient's antibodies can react to. PRA is a measure of the percentage of donors that the patient's antibodies would react against in a given population or panel of HLA types.

The presence of an anti-HLA-A2 antibody indicates a sensitization to that specific HLA type. However, to determine the PRA accurately, the composition of the panel used in testing is crucial. The actual percentage of the population that is A2-positive and other related factors will influence the PRA calculation. Different panels may include a varied representation of HLA-A2 or other HLA types, which could significantly alter the PRA result.

Thus, without knowing the exact makeup of the panel—specifically how many of the tested individuals express HLA-A2—it is impossible to determine an exact PRA percentage. The question therefore emphasizes the importance of the panel's composition in interpreting the significance of the anti-HLA-A2 antibody in terms of PRA.