THE IMMUNOGLOBULIN-G FRACTION FROM PLASMA CONTAINING ANTIPHOSPHOLIPID ANTIBODIES CAUSES INCREASED PLACENTAL THROMBOXANE PRODUCTION

OBJECTIVE: Our objective was to evaluate whether the immunoglobulin G fraction from plasma containing high levels of antiphospholipid antibodies alters the production of prostacyclin or thromboxane when incubated with normal human placental tissue. STUDY DESIGN: The immunoglobulin G fraction was prepared from the pooled plasma of five volunteers with normal obstetric histories and no antiphospholipid antibodies. The immunoglobulin G fraction was prepared similarly from a patient with the antiphospholipid antibody syndrome. Doses of these immunoglobulin G fractions ranging from 0.3 to 3.0 mg were incubated with placental explants obtained from eight normal pregnancies, and prostacyclin and thromboxane production was assessed over 48 hours. RESULTS: Placental prostacyclin production was unaltered by incubation with either immunoglobulin G fraction at any of the doses tested. Placental thromboxane production tripled by 32 hours with the addition of 0.6, 1.5, and 3.0 mg of the antiphospholipid antibody traction (p < 0.05) compared with baseline production but was unaltered by the addition of the normal pooled plasma fraction at any dose. The increase in thromboxane production with antiphospholipid antibody immunoglobulin G appeared to be dose related. CONCLUSION: The immunoglobulin G fraction prepared from plasma containing antiphospholipid antibodies caused increased placental thromboxane production without altering prostacyclin production.