Nonspecific immunity in pregnancy: monocyte surface Fc γ receptor expression and function

Abstract

The state of pregnancy is an immunological enigma during which the body must prevent rejection of the antigenically foreign fetus while at the same time maintain sufficient maternal host defense mechanisms to combat infection. Although most studies on the immunology of pregnancy focus on immune suppression, several studies have shown an increase in nonspecific host defense, which is postulated to be a compensatory mechanism for decreased specific immunity during pregnancy. Studies in this laboratory have shown that monocyte surface Fc γRI (CD64) and Fc γRII (CD32) expression progressively increase throughout pregnancy, while surface MHC class II expression remains unchanged. Functional studies revealed that the number of phagocytic monocytes which could be isolated from pregnant women was increased. These cells exhibited an increased capacity to ingest IgG-opsonized human erythrocytes. This study shows for the first time that monocyte surface Fc γR expression and Fc γR-mediated functions are increased during pregnancy. These results support the hypothesis that nonspecific immunity as represented by Fc γR expression and function is increased during pregnancy.