Study on nonspecific immunity in pregnant women: II. Effect of hormones on chemiluminescence response of peripheral blood phagocytes.

To analyze the mechanisms of increased nonspecific immunity in pregnant women, the effect of various hormones on the phagocytic activity was estimated by a luminol-dependent chemiluminescence (CL) response during phagocytosing opsonized zymosan. The CL response of whole blood supplemented with exogenous human chorionic gonadotropin (hCG) increased significantly in all the male and female subjects and pregnant women. An approximate two- to fourfold increase was observed in comparison with the unsupplemented control in each subject at concentrations ranging from 1 to 1,000 IU/ml after 48 h of incubation (P less than 0.05). Progesterone slightly stimulated the CL response in female subjects only, but had no effect on male and pregnant women. Estradiol (E2) did not stimulate the CL response in any subject. The expression of Fc and C3b receptors on the surface of polymorphonuclear leucocytes (PMNL) in pregnant women was also investigated by measuring the immunofluorescence stained with monoclonal antibody to Fc and C3b receptors, respectively. The relative numbers of Fc receptors increased significantly in the third trimester compared to those of female control (P less than 0.05). Those of C3b receptor also increased in the second and third trimester (P less than 0.005). These results suggested that the nonspecific immunity represented by phagocytic activity in pregnant women increased with both oxidative metabolic responsiveness and the expression of membrane receptors. Besides, the increased phagocytic activity of the maternal host is probably due to the stimulatory effect of both endogenous and exogenous hCG on their peripheral blood phagocytes.