Normal expression of tissue factor, thrombomodulin, and annexin V in placentas from women with antiphospholipid syndrome

OBJECTIVE: Placentas from pregnancies complicated by antiphospholipid syndrome often show thromboses and infarction, which may result from aberrations in placental coagulant pathways. We tested the hypothesis that alterations in tissue factor, thrombomodulin, and annexin V expressions contribute to poor pregnancy outcome associated with antiphospholipid syndrome. STUDY DESIGN: Frozen sections from random biopsy samples of the basal plates of placentas from patients with primary antiphospholipid syndrome (n = 9), patients with secondary antiphospholipid syndrome (n = 3), and gestational age-matched control subjects (n = 10) were immunostained for tissue factor, thrombomodulin, and annexin V. Intensity of immunostaining was assessed by means of quantitative image analysis. Annexin V protein expression was evaluated with Western blotting techniques. RESULTS: Tissue factor was expressed in the perivascular cells of the villous vasculature. Thrombomodulin and annexin V immunostaining was localized to the syncytiotrophoblast. There were no differences in the intensity of immunostaining for tissue factor, thrombomodulin, and annexin V between placentas from women with antiphospholipid syndrome and those from control subjects. Western blot analysis of annexin V expression showed no differences between study patients and control subjects. CONCLUSION: Alterations in placental coagulant pathways involving tissue factor, thrombomodulin, and annexin V do not contribute to poor pregnancy outcome associated with antiphospholipid syndrome.