Placental and maternal serum inhibin-A and activin-A levels in Down's syndrome pregnancies

The objective of this study was to analyse the levels of inhibin-A and acti vin-A in maternal serum and placental tissue from Down's syndrome (DS) preg nancies. Inhibin-A and activin-A levels were determined by specific immunoa ssays and individual results were expressed as multiples of the control med ian (MoM) at the appropriate gestation. Immunohistochemistry was used to lo calize inhibin alpha and beta (A)-subunits in a selection of placental sect ions. In DS pregnancies, median inhibin-A levels were found to be significa ntly elevated to 1.46 MoM (P<0.05) in placental extracts, and 2.06 MoM (P<0 .0001) in maternal serum, when compared with uncomplicated pregnancies. Med ian activin-A MoMs were also elevated in placental extracts and maternal se rum to 1.62 MoM (P<0.01), and 1.26 MoM (P<0.05), respectively. Immunohistoc hemistry revealed that the alpha subunit of inhibin-A and the beta (A) subu nit of inhibin-A and activin-A were mainly localized to the trophoblastic l ayer of placental villi. Semiquantitative studies of staining intensity rev ealed a trend towards stronger staining of placental trophoblasts and strom a of DS tissues, although this was statistically significant only for beta (A) subunit staining of trophoblasts (P<0.05). These results support the hypothesis that maternal serum levels of inhibin- A and activin-A are elevated due to increased production in the placenta, a nd increased immunostaining of trophoblasts suggests that this may be due t o increased production in the trophoblasts. (C) 2001 Harcourt Publishers Lt d.