THROMBOGENIC PROPERTIES OF ANTIPHOSPHOLIPID ANTIBODIES DO NOT DEPEND ON THEIR BINDING TO BETA(2) GLYCOPROTEIN-1 (BETA(2)GP1) ALONE

Immunization of mice with beta(2)glycoprotein 1 (beta(2)GP1) induces p roduction of antiphospholipid (aPL) antibodies, which were shown to ha ve thrombus enhancing properties in an experimental mouse model, indic ating that these antibodies are thrombogenic in vivo. To determine whe ther the thrombogenic effect of murine antiphospholipid antibodies is due to their aPL or their anti-beta(2)GP1 activity, we injected mice w ith murine monoclonal anticardiolipin (aCL) and anti-beta(2)GP1 antibo dies. Effects of these antibodies on thrombus formation, was evaluated utilizing a mouse model which enables kinetics of thrombus;formation to be studied.The results of this study showed that the size of the th rombus in animals injected with murine aCL antibodies was larger than that in control groups. There was no difference in thrombus kinetics b etween anti-beta(2)GP1 injected mice and controls, suggesting that the thrombogenic effect of aPL antibodies is not related to their anti-be ta(2)GPI activity alone. Mice receiving monoclonal antibodies with bot h aCL and anti-beta(2)GP1 activity, also increase thrombus size when c ompared with controls. These data indicate that murine aCL, but not an ti-beta(2)GP1, antibodies are thrombogenic in vivo.