QUANTIFICATION OF THE PREGNANCY-SPECIFIC BETA-1-GLYCOPROTEIN (SP1) BY IMMUNOPRECIPITATION TECHNIQUES - INFLUENCE OF A CROSS-REACTING HIGH MOLECULAR-WEIGHT ALPHA-2-PROTEIN

Two serum proteins with SPI determinants were separated by means of size chromatography and preparative zone electrophoresis. One of the proteins had β1 electrophoretic mobility and an estimated molecular weight of 90,000, and the other had Ş‐mobility and a molecular weight around 400,000. When available antibody preparations to SPI were used, the high molecular weight protein formed immunoprecipitates only when polyethyleneglycol (PEG) was added to the agarose. It is shown that the high molecular weight protein has a pronounced effect on quantification of SPI by rocket immunoelectrophoresis, whereas the effect was less pronounced but still considerable when quantification was performed by radial immunodiffusion. Copyright © 1979, Wiley Blackwell. All rights reserved