LONGITUDINAL-STUDIES SHOWING ALTERATIONS IN LEVELS AND FUNCTIONAL RESPONSE OF LYMPHOCYTE-T AND LYMPHOCYTE-B IN HUMAN PREGNANCY

Abstract

Altered blood levels of T [thymus-derived] and B [bone marrow derived] lymphocytes were found in the 1st half of human pregnancy. A total of 22 women were tested, using direct or indirect rosetting assays or the fluorescence-activated cell sorter, to determine the levels of peripheral blood T and B cells. In all cases, an inversion of T and B cell levels was observed, i.e., T cell levels were decreased and B cell levels (as measured by the presence of surface immunoglobulin or the presence of B cell surface antigens) were increased. This inversion was exhibited as early as 1 wk post-implantation. Lymphocytes from 2 of the women were also examined for stimulation with phytohemagglutinin (PHA) and pokeweed mitogen (PWM) at intervals during gestation, and the amount of [3H]thymidine uptake was compared to that of 2 non-pregnant women tested at each interval. The values obtained for the pregnant women with PHA were markedly lower, and with pokeweed mitogen slightly lower, than those of non-pregnant controls. The PHA and PWM values in the pregnant women returned to levels similar to those of the non-pregnant women shortly after the T and B cells returned to normal. The decrease in the response of the lymphocytes to mitogens during early pregnancy appears to parallel the numerical deficiency of T cells.