P38An Acute Hemolytic Transfusion Reaction Due to Anti-Wra Antibodies.

The Wr^a antigen is found on the red blood cells of approximately 1 : 1000 caucasians. Anti-Wr^a antibodies have been reported to be present in 1 : 25 to 1 : 100 healthy blood donors and an even higher proportion of hospital patients. Wr^a incompatibilty might therefore be expected to occur in approximately one in 50,000 blood transfusions. Reports of hemolytic transfusion reactions (HTR) and hemolytic disease of the newborn (HDN) due to anti-Wr^a are however rare. We report an acute HTR due to anti- Wr^a in a 58 year old male with MDS associated with rigors, shortness of breath and a significant rise in serum bilirubin from 16 μmol L⁻¹ pre-transfusion to 110 μmol L⁻¹ immediately afterwards. This was accompanied by the appearance of bilirubin and urobilinogen in his urine and a fall in haemoglobin of nearly 2 g dL⁻¹ following the transfusion. Anti- Wr^a was the only antibody implicated. Wr^a antigen expressing reference panel cells and the unit being transfused during the gave 2–3+ reactions by IAT against the recipient's plasma. The donation typed as positive with Wr^a antisera. The recipient typed as Wr^a antigen negative. The reaction resulted in the patient being admitted to hospital for 2 days. The increasing use of electronic issue may result in more frequent reports of reactions due to anti-Wr^a as commonly used screening cells do not express this antigen.