Hemolytic transfusion reaction due to anti-Tc(a)

Anti-Tc(a) detects a high-incidence antigen in the Cromer blood group system. Cromer system antibodies have not usually been associated with hemolytic transfusion reactions or hemolytic disease of the newborn.

Anti-Tc(a) (initially identified in the patient's serum in 1982) was not detected when she was admitted to the hospital with upper gastrointestinal. bleeding. Three units of red cells were administered. The patient was discharged, but was readmitted to the hospital after her hemoglobin fell to 7.1 g per dL. Antibody detection tests remained negative and three additional units were transfused. Over the next 7 days, her hemoglobin steadily fell to 5.5 g per dL. The level of lactate dehydrogenase rose to 1257, the plasma hemoglobin rose to >16 mg per dL, and the haptoglobin decreased to <6 mg per dL. Five days after transfusion, her direct antiglobulin test was weakly reactive with complement-specific antiglobulin reagents. Eluates were nonreactive. Anti-Tc(a) was detected in her serum; no other antibodies were detected. Differential typing failed to detect any circulating Tc(a+) red cells. The antibody was strongly reactive in a monocyte monolayer assay.

Although Cromer system antibodies have generally not been proven to be clinically significant in transfusion therapy, the destruction of red cells from six units of transfused Tc(a+) red cells in this patient indicates that anti-Tc(a) may have destructive potential in some patients.