In the autocontrol used for serologic testing, which components are included?

• A. Patient serum plus patient red blood cells
• B. Patient serum plus donor red blood cells
• C. Donor serum plus patient red blood cells
• D. Donor serum plus donor red blood cells

Answer: (A)

Autocontrol in serologic testing checks whether the patient’s own antibodies react with their own red blood cells, revealing autoantibody activity rather than a reaction to a donor’s cells. To perform it, you test the patient’s serum (or plasma) against the patient’s own red blood cells. If the autocontrol is negative, any reactivity seen with donor cells during screening is more likely due to alloantibodies against non-self antigens. If the autocontrol is positive, it suggests an autoantibody or other non-specific reactivity.

Using patient serum with donor red blood cells would test for antibodies against donor antigens (an alloantibody) but it is not an autocontrol. Donor serum with patient red cells or donor serum with donor red cells do not assess the patient’s own antibody reactivity, so they’re not autocontrols. Therefore, the correct combination is patient serum with patient red blood cells.