Submitted August 21, 2007
Accepted November 8, 2007
Induction of an inhibitor antibody to factor XI in a patient with severe inherited factor XI deficiency by Rh immune globulin
Michal Zucker, Ariella Zivelin, Jerome Teitel, and Uri Seligsohn*
Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel Aviv University, Tel Hashomer, Israel
Department od Medicine, Division of Hematology, St. Michael's Hospital and University of Toronto, Toronto, Canada
* Corresponding author; email: seligson{at}sheba.health.gov.il.
In this paper we report an inhibitor antibody to factor XI (FXI) in a woman with severe inherited FXI deficiency, induced by FXI present in an Rh immune globulin preparation. The patient is homozygous for the Glu117Stop mutation, associated with a FXI level of less than 1U/dL. Unlike all previously described patients with severe FXI deficiency and an inhibitor, the patient had never been exposed to blood products. Following three injections of Rh immune globulin during pregnancy she developed an inhibitor to FXI (8 Bethesda units) which was shown to bind specifically to FXI and inhibit factor IX cleavage by purified FXIa. The administered Rh immune globulin and two other similar products were shown to contain FXI. Clinicians should be aware of the potential for immunization of severely FXI deficient patients by FXI present in Rh immune globulin preparations.
