Effect of Human IgG Antiphospholipid Antibodies on an In Vivo Thrombosis Model in Mice

Abstract

SummaryHigh levels of IgG antiphospholipid antibodies (aPL) have been associated with clinical thrombosis. It is uncertain however whether these antibodies play a direct role in thrombosis or are merely epiphenomena. To investigate whether antiphospholipid antibodies might play a role in thrombosis, we utilized a novel mouse model in which the dynamics of in vivo thrombosis can be studied. CD1 mice (26-30 g) were passively immunized with 25 mg of human IgG from a patient with the Antiphospholipid Syndrome (IgG-APS) (n = 17), IgG from normal pooled sera (TgG-NHS) (n = 9). or saline solution (n = 17), followed by 40 mg of the same preparations at 48 h. At 72 h, levels of human aPL antibodies, detected using the anticardiolipin ELISA test (aCL ELISA test), in mice immunized with IgG-APS, were 50-100 GPL units. Each animal was anesthetized, femoral vein minimally mobilized and subjected to a standardized “pinch” injury to induce thrombosis. The vessel was transilluminated using acrylic optical fibers connected to a light source, and clot formation and dissolution were visualized by a standard surgical microscope equipped with a video camera, video recorder, and computer assisted analysis system. Results showed that average clot size was significantly larger in mice immunized with IgG-APS compared to those treated with saline (p <0.037). In addition, the thrombus persisted longer in a significantly higher number of mice immunized with IgG-APS (10/17) compared to mice immunized with IgG-NHS (1/9) or saline (2/12) (p <0.02). These data suggest that IgG-APS may play a role in thrombus formation in humans. In addition, this study shows the feasibility of using this in vivo murine thrombus model for study of the effects of aPL antibodies.

A Chimeric Protein C Containing the Prothrombin Gla Domain Exhibits Increased Anticoagulant Activity and Altered Phospholipid Specificity

“…These antibodies are associated with an increased risk of thrombosis (67)(68)(69), and there is no detailed understanding of the best in vitro assays to detect the antibodies responsible for the pathogenic response. The development of an APC molecule with no PE dependence will allow the exploration of the mechanisms of PE-dependent lupus anticoagulant effects on the APC system in vitro and in vivo.…”

A monoclonal IgG anticardiolipin antibody from a patient with the antiphospholipid syndrome is thrombogenic in mice.

“…Recently, murine models that demonstrate that passively administered APA can induce fetal loss and thrombosis have been established (26)(27)(28)(29)(30) (1/40), the patient has never manifested rash, arthralgias, arthritis, organic brain syndrome, or serologies suggestive of lupus. The antithrombin activity (determined by chromogenic assay kit, Organon Technika-Cappel) and plasma levels of proteins C and S (determined by Laurell rocket immunoelectrophoresis) were normal.…”

“…Thrombogenic Properties of Monoclonal ACA IS2. An animal model was used to determine the thrombogenic potential of the two mAbs (29). An initial exploratory study indicated that passively administered IS2, but not IS1, was thrombogenic in the CD1 mouse when compared with polyclonal NH IgG (data not shown).…”

“…The mouse model of thrombosis employed in this study has been described in detail (29). Briefly, CD1 mice (25-30 g, 4-8 weeks old, Charles River Breeding Laboratories) were injected i.p.…”

The epidemiology of the antiphospholipid syndrome: Who is at risk?

“…However, Pierangeli et al [13] reported that mice passively immunized with a high quantity of aCL antibodies and subjected to pinch injury of the femoral vein showed larger and more persistent thrombi than did controls.…”