Abstract
The patient was a 22-year-old female diagnosed as having acute myeloid leukemia. The ABO blood typing test using anti-A showed mixed field agglutination by both the tube test and the column agglutination technology on admission. The transferase activity of A antigen was stable. The A antigen activity decreased after the start of remission-induction therapy, and disappeared on the 11th day after admission. She was transfused with two units of group A, D-positive red blood cells (RBCs) on the same day, and the A antigen activity increased to (4+) (256 times) on the 14th day. Interestingly, in this case, at the time when the A antigen activity of RBCs decreased in the body, the A antigen activity also decreased simultaneously in blood samples kept in cold storage. However, the A antigen activity did not decrease even in cold storage after reactivation. The cause of the decrease in ABO antigen activity in leukemia still remains incompletely clarified. In this case, the decrease in A antigen activity is considered to be closely associated with the weakness of A antigen structure because the A antigen activity of RBCs in the body and cold storage decreased at the same time.
