Delayed hemolytic transfusion reactions.

Delayed hemolytic transfusion reactions continue to occur in spite of the use of all of the currently available techniques of antibody detection. Both low titers of the antibodies and dosage effects appear to contribute to the failure of detection. A rapid anamnestic response can occur with transfusion of the appropriate antigen. The clinical as well as the laboratory presentation of delayed hemolysis may vary from case to case and thus confuse the true nature of the reaction. The Kidd antibodies are, as a group, more frequently reported in delayed reactions than are any other antibodies.