The immunoglobulin G fraction from plasma containing antiphospholipid antibodies causes increased placental thromboxane production.

Abstract

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. 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. 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 fraction (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. The immunoglobulin G fraction prepared from plasma containing antiphospholipid antibodies caused increased placental thromboxane production without altering prostacyclin production.