Overproduction of Antiplatelet Antibody against Glycoprotein IIb after Splenectomy in a Patient with Evans Syndrome Resulting in Acquired Thrombasthenia

We treated a 33-year-old female with Evans syndrome. She received high dose gamma globulin, prednisolone, and azathioprine, and her platelet count transiently increased. After splenectomy, the platelet count markedly increased. However, the bleeding tendency worsened and the bleeding time was prolonged. A platelet defect, characteristic of thrombasthenia, was found. Antigen-captured ELISA and Western blotting revealed that the patient’s serum had an IgG autoantibody against platelet membrane glycoprotein IIb and the patient’s plasma inhibited normal platelet aggregation. These findings suggest that overproduction of the antiplatelet antibody is triggered by platelet recovery due to splenectomy and affects platelet function resulting in acquired thrombasthenia.