Peripheral polymorphonuclear leukocyte priming contributes to oxidative stress in early pregnancy.

OBJECTIVE: The cause of elevated blood leukocyte count in pregnancy is unknown. We hypothesized that priming of peripheral polymorphonuclear leukocytes (PMNL) caused this elevation. METHODS: Eleven women in the first trimester of pregnancy were included in this prospective study. Peripheral venous blood was drawn twice from each woman, before and after a medical abortion (pregnant and nonpregnant, respectively). Complete blood cell count, plasma alkaline phosphatase (ALP), and rate of superoxide release from separated phobrol 12-myristate-13-acetate (PMA)-stimulated PMNL were determined. RESULTS: The PMNL count in early pregnancy was significantly higher, with a significant increase in the PMNL rate of superoxide release compared to the nonpregnant state. A linear correlation between the rates of superoxide release and PMNL counts before and during pregnancy was found. ALP levels were significantly elevated in early pregnancy. CONCLUSION: The increased PMNL count is probably a compensatory response to PMNL priming. The increased rate of superoxide release from primed PMNL may contribute to oxidative stress in early pregnancy.