The effect of low-molecular weight dextran on erythrocyte aggregation in normal and preeclamptic pregnancy.

Erythrocyte aggregation was determined by a novel method enabling the quantification of the aggregation process in whole blood. Blood samples of 47 healthy pregnant women and 39 preeclamptic patients were examined. Subjects within each group were matched for the gestational age. It was found that RBC aggregation increases with the gestational age in healthy pregnancy and further increases in preeclampsia. Addition of low-molecular weight dextran (MW = 9300) to blood samples of both healthy pregnant women and preeclamptic patients reduces RBC aggregation in a concentration-dependent manner. The obtained results indicate alterations in plasma composition as the primary factor for the increased RBC aggregation in both normal and pathological pregnancy. It is suggested that adsorption of low-molecular weight dextran on the RBC membrane reduces the surface concentration of plasma bridging molecules thereby reducing RBC aggregation toward normal.