Induction of high levels of anticardiolipin antibodies in mice by immunization with β2-glycoprotein I does not cause fetal death,

OBJECTIVE: Our purpose was to determine whether anticardiolipin antibodies induced by immunization with β2-glycoprotein I cause fetal death in mice. STUDY DESIGN: Female BALB/c mice were immunized with β2-glycoprotein I in a carbohydrate adjuvant or with carbohydrate adjuvant alone. The mice were mated with BALB/c malee and killed on day 11 to 13 of pregnancy, and the fetal status was determined. Posttreatment blood samples were obtained for measurement of anticardiolipin and anti-β2-glycoprotein I antibodies and platlet counts. RESULTS: Anticardiolipin and anti-β2-glycoprotein I antibodies developed in all mice immunized with β2-glycoprotein I. Fetal death occurred in 17 of 145 gestational sacs (12%) in 18 mice immunized with β2-glycoprotein I compared with 24 of 177 (14%) sacs in 21 control mice. There were no morphometric or histologic differences between gestational tissues, and platelet counts were similar for each group. CONCLUSIONS: The induction of high levels of anticardiolipin antibodies in BALB/c mice by β2-glycoprotein I immunizations did not result in fetal death or thrombocytopenia. These nonpathogenic β2-glycoprotein I-induced anticardiolipin antibodies should prove useful in the characterization of clinically relevant epitopes for antiphospholipid syndrome.