Mononuclear cell subpopulations during normal pregnancy: I. Analysis of cell surface markers using conventional techniques and monoclonal antibodies.

Previous reports indicate depression of cellular immunity during pregnancy. In order to get a deeper insight into the immunoregulatory subsets of mononuclear cells in pregnant women, we analyzed the percentages of T and B lymphocytes, T cell subsets and cells expressing IgG-Fc and C3 receptors, and M1- and Ia-like antigens in venous blood samples from healthy women and pregnant women at different gestational ages and after delivery. Even if a trend toward a progressive decrease of T lymphocytes and T4+ helper subset was observed throughout pregnancy, along with a slight increase in the percentages of cells bearing C3 receptors, M1, and Ia-like antigens in the second trimester of gestation, analysis of variance of our data did not demonstrate statistical significance in the observed changes. Therefore we conclude that the pregnancy-induced suppression of maternal responsiveness towards alloantigens and/or mitogens is not reflected by significant changes in the distribution of circulating mononuclear cells and immunoregulatory T-lymphocyte subsets as defined by the currently available surface marker techniques.