A severe haemolytic transfusion reaction caused by anti-Le(a) active at 37 °C.

Abstract

Anti-Lea antibodies may be detected in antenatal red blood cell (RBC) antibody screening and in pretransfusion tests. It has been suggested that these antibodies can result from alloimmunisation, but they may also appear spontaneously, for example, in pregnant women1. Most anti-Lea are IgM antibodies that react only at low temperatures. They are, therefore, considered harmless, and in many centres Le(a+) test cells are not mandatory in routine screens. Haemolytic transfusion reactions caused by alloantibodies against the Lewis blood group antigen Le(a) are rare, but have been described2–10. The patients in these reported cases were transfused for different reasons, including gynaecological bleeding2,4,5, gastrointestinal operations or bleeding3,9,10, leukaemia8, and infection7. In one experimental study6, it was demonstrated that pre-treatment with Lewis substance could weaken a subsequent in vivo reaction to transfused Le(a)+ cells in a patient with a spontaneous anti-Lea. Most reports concluded that the anti-Lea antibody was of spontaneous origin3–6,9, but in several other cases it could not be determined whether the antibody was spontaneous or resulted from immunisation by previous incompatible transfusions2,6,7,10. Despite this, a property of the anti-Lea antibodies identified was their in vitro reactivity at 37 °C against Le(a)+ test cells, although this was not directly tested in one report10. The signs and symptoms of the transfusion reaction in all cases were similar but of different severity, and included rapid onset of low back pain, nausea, vomiting, chills, red-coloured urine and transient anuria. Altogether, they suggested intravascular haemolysis. There were no fatal reactions. The reports on severe haemolytic transfusion reactions caused by anti-Lea antibodies referenced here were published between 1949 and 1963. It was surprising to us that no reports of similar reactions have been published more recently and it is not known how frequent reactions caused by anti-Lea are today. One explanation for the lack of reports could be that severe reactions caused by anti-Lea have disappeared due to more efficient pre-transfusion testing. This would, however, seem unlikely since many countries, including Sweden, use type-and-screen as pre-transfusion testing, and Le(a)+ test cells are not mandatory in the routine screen. Because of the severity of reactions that might occasionally occur in patients carrying an anti-Lea antibody active at 37 °C, we believe these antibodies should not be forgotten and that reporting additional cases is warranted. We here describe a case of severe acute haemolytic transfusion reaction, caused by a presumed IgM anti-Lea alloantibody, in a patient with chronic lymphocytic leukaemia (CLL) with autoimmune haemolytic disease.