Nucleated erythrocytes in enriched and unenriched peripheral venous blood samples from pregnant and nonpregnant women.

The presence of nucleated erythrocytes was studied before and after enrichment with immunomagnetic beads and monoclonal antiglycophorin A (anti-GPA) antibody in the peripheral venous blood of 11 pregnant women at 10-16 weeks of gestation. Nucleated erythrocytes were identified by alkaline phosphatase antialkaline phosphatase immunostaining by means of anti-GPA antibody. In the unenriched cell samples, nucleated erythrocytes were found at frequencies of 1/2,800-1/83,000 in 6 cases. The frequency of nucleated erythrocytes was increased up to 6 times by the enrichment.