Hemolysis following platelet transfusions from ABO-incompatible donors.

Two hemolytic transfusion reactions related to isoagglutinins present in group O platelet concentrates are reported. The first, a severe reaction in a group A 10-kg patient, resulted from transfusion of 200 ml of plasma containing a hemolytic anti-A, titer 16, and an IgG anti-A, titer of 32,000. In the second case, a group B adult received between 50 and 70 ml of O plasma with a titer (16,000) of anti-B. This was followed by hemolysis of approximately 40 percent of the patient's red cell volume.