The Role of Peripheral Blood Monocyte on Cell‐Mediated Immunity in Pregnant Women

In this work, we studied the monocyte function as accessory cells to T‐cells during and after pregnancy. The function tended to decrease in the 1st trimester, but showed a significant increase in the 3rd trimester (p<0.01). After parturition, it returned to normal. Next, the effect of pregnant serum on the monocyte function was studied. Pregnant serum was found to enhance the monocyte function, and this was most apparent in the samples obtained in the 3rd trimester. These facts led us to study the roles of a number of hormones whose serum levels change dynamically during pregnancy. We found that the monocyte function was enhanced 41% when estrogen was added in concentrations equivalent to the in vivo level during the 3rd trimester, and inhibited 40% by cortisol. These observations suggest that monocytes play an important role in cell‐mediated immunity during pregnancy and that pregnant serum, especially hormones, influence the monocyte function.