Abstract
Emm is a high-frequency antigen classified as the blood group system of the ISBT 901 series. Although eight cases of anti-Emm have so far been reported overseas, none were transfused; thus, its clinical significance remained unknown, and the antibodies may be "naturally-occurring". Moreover, there have been no such reports in Japan. We encountered the first case of a Japanese patient (58-year-old, man) with anti-Emm who developed an acute hemolytic transfusion reaction caused by crossmatch-incompatible RBCs. In this case, anti-Lea was identified in the patient's plasma by pretransfusion testing as one of his irregular antibodies. One bag of crossmatch-incompatible Le (a-) RBCs had to be transfused. Thirty minutes after transfusion, his blood pressure had dropped, and hemoglobinuria was observed. However, he was subsequently transfused with an additional two bags of RBCs on the same day, and he was further transfused with one more bag of RBCs three days later, without any hemolytic transfusion reaction. On the sixth day, after the transfusion of 30 ml of RBCs, the patient vomited, and his urine was cola-colored; the transfusion was then stopped. Thereafter, anti-Emm was identified by further examinations. This case suggests that anti-Emm may be clinically significant and considered to be a "naturally-occurring" antibody.
