• Prostaglandins;
  • adherent cells;
  • lymphocyte response;
  • pregnancy

ABSTRACT: The lymphocyte response to optimal and suboptimal doses of phytohemagglutinin (PHA) has been investigated in 33 healthy pregnant women compared with 27 controls. Standard preparations of lymphocytes, isolated from the two groups of participants by Ficoll-Metrizoate density gradient centrifugation, contained the same amount of peroxidase positive cells (± 10%) and exhibited the same response to PHA. Removal of cells adhering to plastic dishes (AC) led to an increased lymphocyte response in pregnant subjects but to a reduced response in the controls. Maternal lymphocytes depleted in AC had a significantly higher PHA response than did AC-depleted lymphocytes from the control subjects. The apparent suppressor activity of AC on maternal lymphocytes is not mediated by prostaglandins as shown by the observations that indomethacin (10−6 M) had the same enhancing effect and prostaglandin E1 (10−6 to 10−8 M) the same inhibiting effect in the two groups of subjects. Collectively the data indicate that during pregnancy the cellular interactions involved in the lymphocyte response to PHA are altered; the data also explain some of the contradictory results in the literature.