VARIATION IN DETECTION OF VEGF IN MATERNAL SERUM BY IMMUNOASSAY AND THE POSSIBLE INFLUENCE OF BINDING-PROTEINS

Using radioimmunoassay (RIA) and a polyclonal antibody we have shown t hat maternal serum vascular endothelial growth factor (VEGF) is elevat ed during pregnancy. In contrast, a commercial VEGF ELISA utilizing a sandwich two-site immunoassay was unable to detect VEGF in 19 of the 2 0 maternal serum samples analysed. In addition, the recovery of exogen ous VEGF added to the pregnancy samples was low or not recordable with the ELISA. Using RIA, 82-101% of the added VEGF was recovered. These differing results could be explained by the formation of VEGF-protein complexes that are detectable using RIA but undetectable with the ELIS A. Our data imply that there is a substantial increase in circulating VEGF binding proteins during pregnancy. The increase in VEGF and its b inding proteins during pregnancy may reflect important physiological e vents in the mother and fete-placental unit.