Acute hemolytic transfusion reaction due to anti-Le(b)

Anti-Le(b) is usually a clinically insignificant antibody of immunoglobulin M subclass most often found in the sera of pregnant women or individuals that are Le(a-b-). We report a case of an acute hemolytic transfusion reaction due to a hemolytic anti-Le(b) that was not seen in the pretransfusion antibody detection test, but was strongly reactive in posttransfusion testing.

A 30-year-old African-American woman with metastatic renal cell carcinoma was receiving chemotherapy. She was anemic with hemoglobin (Hb) of 7.2 g/dL and had a negative antibody detection test by the solid-phase red blood cell adherence method. She was transfused with 2 RBC units without incident. Nine days later her Hb was 7.9 g/dL again with a negative antibody detection test. Transfusion of an additional RBC unit was begun. During the transfusion she developed chills, nausea, hypertension, and red-brown urine. The posttransfusion sample plasma was grossly hemolyzed with a strongly positive direct antiglobulin test (DAT) by gel. By comparison the pretransfusion plasma was normal appearing and the DAT was weaker. The eluate was negative on both occasions. Anti-Le(b) was detected in the posttransfusion sample by MTS gel (Ortho Diagnostics). Both RBC units she had received before the RBC unit that caused the reaction were Le(b+) as was the implicated RBC unit.

This case illustrates that anti-Le(b) which is usually clinically insignificant can occasionally cause severe hemolytic transfusion reactions. Only three other reported cases of anti-Le(b) causing hemolytic transfusion reactions could be found in the literature, two of which were in abstract form only.