Complex formation of pregnancy-specific alpha 2-glycoprotein (SP1 alpha) and heparin

The Schwangerschaftsprotein 1 (SP1)alpha values in blood measured by rocket immunoelectrophoresis are affected by the addition of anticoagulants. When compared with values in serum, those in heparin plasma were much higher, while those in sequestrene ethylenediamine-tetra-acetic acid), sodium citrate and fluoride oxalate were lower. On the other hand, SP1 and SP1 beta concentrations were not significantly affected in heparin or sequestrene and were only slightly depressed in sodium citrate and fluoride oxalate. The effect of heparin on SP1 alpha in serum was dose-dependent. We surmise that SP1 alpha forms a complex with heparin and that it may be involved in the coagulation system in pregnancy.