In the described indirect antiglobulin test scenario, which statements are true?

• A. Antihuman globulin reagent was added
• B. Adequate washing of cells was performed
• C. Antiglobulin serum has not reacted with the original red blood cells being tested
• D. All of the above

Answer: (A)

In an indirect antiglobulin test, antibodies in the patient's serum are allowed to bind to donor red cells during incubation. After washing away unbound components, antihuman globulin reagent is added. The AHG reagent reacts with the antibodies that are already attached to the red cells, causing agglutination if those antibodies are present. This step is the key detector in the test, so adding the antihuman globulin reagent is the correct statement. Adequate washing is important to avoid nonspecific reactions, but since the scenario centers on the presence and action of the AHG reagent, that detail isn’t the asserted truth here. The idea that the antiglobulin reagent has not reacted with the red cells contradicts how the test confirms antibody binding, so it isn’t correct.