Unusual Response to ABO Incompatible Blood Transfusion

Three units of group A blood were inadvertently administered to a group O recipient during surgery without evidence of hemoglobinemia, hemoglobinuria, hypotension, disseminated intravascular coagulation, acute renal tubular necrosis, or other signs and symptoms of transfusion reaction. The recipient had normal concentrations of IgG, IgA, and IgM as well as complement (C3) prior to transfusion and anti‐A agglutinins titered to 64 (titer of 128 by the antiglobulin technique). Seventeen hours following the transfusion, 28 per cent of the circulating red blood cells were group A (equivalent to 475 ml of packed cells); they were eliminated by day 5 without evidence of hemoglobinuria, hemoglobinemia or hyperbilirubinemia. Anti‐A titers (antiglobulin) had risen from a posttransfusion low of 4 to 4,096 by day 10. After treatment of serum with 2‐mercaptoethanol, however, hemolytic activity which was first noted on day 5 was lost and the antiglobulin titer dropped to 24 which suggested that most of the anti‐A produced in response to the transfusion was IgM rather than IgG. The anti‐A titer had dropped to essentially pretransfusion levels and the majority of anti‐A present was IgM by day 91. The recipient suffered no untoward effects from the transfusion and was in good health three months following the transfusion.