Delayed hemolytic transfusion reaction caused by the second example of anti-K19.

A second example of anti-K19 has been identified in the serum of a black patient immunized by blood transfusions. The antibody was responsible for delayed hemolysis of transfused incompatible red blood cells. The patient's red blood cells are K:--19 but are otherwise of common Kell phenotype. The K19 antigen is closely associated with the Kell blood group although there is, as yet, no pedigree information to confirm that it is produced by the Kell gene. Tests on 10,757 group O blood donors have not revealed any further examples of the K:--19 phenotype.