Glycosylation of pregnancy-associated plasma protein a (PAPP-A) in normal and trisomic pregnancies: Studies with lectins

Abstract

Summary Glycosylation of serum PAPP-A in normal pregnancies and in first trimester pregnancies affected by fetal trisomy 21 (T21) was studied using the immobilized lectins Ulex europaeus 1, Lens culinaris, Maackia amurensis and Sambucus nigra . First trimester maternal serum PAPP-A concentration in the T21 group (42 samples) was significantly reduced (46% of the controls). No difference in binding to any lectin, however, was observed between normal and T21 first trimester serum PAPP-A. In normal pregnancy (123 samples), PAPP-A from different gestational weeks was investigated. Its concentration increased between weeks 9 and 25. An increase in the fraction binding to LCL occurred after the first trimester while the MAA-binding fraction was decreasing, indicating a reduction in the content of (α-2,3)-linked sialic acid with unmasking of glucose/mannose residues. Since, in T21, placental PAPP-A production is not reduced (opposite to its serum concentration), our observations could indicate a shift in the dominating source of PAPP-A production from the mother to the placenta after the first trimester.