A severe transfusion reaction associated with anti‐EnaTS in a patient with an abnormal alpha‐like red cell sialoglycoprotein

A 71‐year‐old woman (Ped) received 3 units of red cells (RBCs), compatible by the indirect antiglobulin test but strongly (4+) incompatible by direct agglutination at 37°C. The next day, her plasma hemoglobin was 1252 mg percent and the direct antiglobulin test (DAT) was weakly positive (IgG and C3). Less than 5 percent of the transfused cells could be detected 48 hours posttransfusion. Her clinical condition deteriorated and renal failure developed. The patient died of pulmonary embolism. Her serum contained a strong (4+) IgM agglutinin and a weakly reactive (microscopically positive) IgG antibody, with anti‐EnaTS specificity. EnaFS and EnaTS antigens were severely depressed or absent from the patient's RBCs; the ficin‐ resistant Ena antigen (EnaFR) appeared to be present. Pretransfusion RBC sialic acid level was 53 ± 2 percent of normal. The patient's RBC membranes were shown to contain sialoglycoproteins beta and delta by sodium dodecyl sulphate polyacrylamide gel electrophoresis with periodic acid Schiff's base staining, with weak staining of components in the regions corresponding to alpha, alpha 2 and alpha delta. The nature of these components was not identified, but their presence suggested that the patient's RBCs expressed a previously undescribed sialoglycoprotein alpha variant.