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Factor XIII in Primary Antiphospholipid Syndrome
PAUL R.J. AMES, LUIGI IANNACCONE, JOSE DELGADO ALVES, ANNAMARIA MARGARITA, LUIS R. LOPEZ, and VINCENZO BRANCACCIO
ABSTRACT.
Objective. To evaluate the clinical significance of factor XIII (FXIII) in primary antiphospholipid syndrome (APS). Methods. A cross-sectional study including patients with primary APS (n = 29), persistent carriers of idiopathic antiphospholipid antibodies (aPL) with no history of thrombosis (n = 14), thrombotic patients with inherited thrombophilia (n = 24), healthy controls (n = 28), and patients with mitral and aortic valve prosthesis (n = 32, as controls for FXIII only). FXIII and fibrinogen were measured by functional assays: IgG anticardiolipin antibody (aCL), IgG anti-ß2-glycoprotein I (anti-ß2-GPI), and plasminogen activator inhibitor (PAI) by immunoassay; and paraoxonase activity by paranitrophenol formation. Intima-media thickness (IMT) of carotid arteries was determined by high resolution sonography. Results. FXIII activity (FXIIIa) was highest in primary APS (p = 0.001), particularly in patients with multiple occlusions (n = 12) versus those with single occlusion (158 ± 45% vs 118 ± 38%; p = 0.02). In primary APS, FXIII positively correlated with PAI (p = 0.003) and fibrinogen (p = 0.005). Similarly in the thrombotic control group, FXIIIa correlated with PAI (p = 0.05) and fibrinogen (0.007). In primary APS, FXIIIa was related to the IMT of all carotid artery segments (p always < 0.01). In thrombotic controls FXIIIa correlated only to the IMT of the common carotid (p = 0.01). In primary APS, FXIIIa was strongly associated with IgG aCL and IgG anti-ß2-GPI (p = 0.005 for both). These associations were weaker in the aPL group (FXIIIa with IgG aCL, p = 0.02, with IgG anti-ß2-GPI, p = 0.04). Conclusion. Enhanced FXIII activity may contribute to atherothrombosis in primary APS via increased fibrin/fibrinogen cross-linking. This pathway is not exclusive to primary APS, being present also in thrombotic controls, but the presence of IgG aPL may favor a higher degree of FXIIIa activation in the primary APS group. (J Rheumatol 2005;32:1058-62) Key Indexing Terms:
ANTIPHOSPHOLIPID ANTIBODY
From the Academic Department of Rheumatology, Leeds General Infirmary, Leeds, UK; Pharmacology Department, Faculty of Medical Sciences, New University of Lisbon, Lisbon, Portugal; Corgenix, Westminster, Colorado, USA; and Angiology and Coagulation Units, Cardarelli Hospital, Naples, Italy. Supported by Praxis Grant 436.00/27699, Foundation for Science and Technology, Portugal (J. Delgado Alves). P.R.J. Ames, MD, Academic Department of Rheumatology, Leeds General Infirmary; J. Delgado Alves, MD, PhD, Pharmacology Department, New University of Lisbon; L.R. Lopez, MD, Corgenix; A. Margarita, MD; L. Iannaccone, BSc; V. Brancaccio, MD, Angiology and Coagulation Units, Cardarelli Hospital. Address reprint requests to Dr. P.R.J. Ames, Academic Department of Rheumatology, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK. E-mail: paxmes@aol.com Accepted for publication January 17, 2005. |