An acquired, calcium-dependent, factor X inhibitor.

Abstract

Acquired factor X (FX) deficiency unrelated to amyloidosis is a rare disorder in which an anti-FX antibody is infrequently detected. A patient with severe bleeding due to a calcium ion-dependent anti-FX IgG antibody is described. The FX affinity purified IgG bound the light chain of FX, but not FX lacking its γ-carboxyglutamic acid domain, and binding was enhanced >1000-fold in the presence of calcium ions. The antibody also recognized prothrombin and factor VII with about 100-fold and 1000-fold lower affinity. Like a lupus anticoagulant, increasing concentrations of phospholipids in functional assays reduced the inhibitory activity of the antibody. The effect of these properties of the inhibitor on laboratory diagnostic studies is considered.

• Authors: George J Broze Jr
• Journal: Blood cells, molecules & diseases (Blood Cells Mol Dis) 2014 Feb-Mar Vol. 52 Issue 2-3 Pg. 116-20 ISSN: 1096-0961 [Electronic] United States
• PMID: 24074948 (Publication Type: Case Reports, Journal Article, Research Support, N.I.H., Extramural)
• Copyright: © 2013.

Chemical References

• Autoantibodies
• Immunoglobulin G
• Phospholipids
• Factor X
• Calcium

Topics

• Aged
• Autoantibodies (blood, immunology, isolation & purification, metabolism)
• Blood Coagulation
• Calcium (metabolism)
• Factor X (antagonists & inhibitors, immunology)
• Factor X Deficiency (blood, immunology, metabolism)
• Humans
• Immunoglobulin G (blood, immunology, isolation & purification, metabolism)
• Male
• Phospholipids (blood, metabolism)