What is the best follow-up test to confirm an alloantibody against a high incidence antigen?

Confirming an alloantibody against a high incidence antigen requires testing against red cells known to lack these antigens. High incidence antigens are present in the majority of the population, meaning that finding a compatible red cell for antibody identification can be challenging.

By specifically testing serum against red cells that are known to lack high incidence antigens, it allows for the identification of the antibody while avoiding cross-reactivity that might occur with a random selection of donor red cells. This focused approach increases the likelihood of confirming the presence of a specific alloantibody, as the test conditions are optimal for detecting reactions against the expected antigens.

Other methods, such as utilizing random donor red cells, could result in non-specific reactions due to the antibodies present in the serum reacting with common antigens. Enzyme-treated autologous red cells may not be as effective for confirming a high incidence antibody either, as enzyme treatments can alter antigen expression and lead to misleading results. Meanwhile, testing an eluate prepared from the patient's red cells is beneficial for identifying antibodies already bound to those cells, but it might not directly confirm the presence of alloantibodies against high incidence antigens as effectively as testing against antigen-negative cells.