A Case of Anti-Kp a Antibody Identified during Preoperative Testing

The Kp a antigen is a low-frequency Kell blood group antigen that is extremely rare in Koreans.Anti-Kp a cannot be detected by routine irregular antibody screening but might be associated with hemolytic transfusion reactions and hemolytic disease of the fetus and newborn.This paper reports a 53-year-old woman in whom anti-Kp a was identified together with anti-Le a during preoperative testing for cervical adenocarcinoma in situ.In the antibody identification test, reactivity with a Kp a -positive reagent red cell was observed at the antiglobulin phase, whereas the reaction was absent or weakened with enzyme-treated cells, showing an atypical serologic pattern.This case shows that antibodies against low-frequency antigens may be missed by routine screening and highlights the importance of the careful interpretation of reactivity with low-frequency antigen-positive reagent cells during antibody identification.(Korean J Blood Transfus 2026;37:96-101)