Plasma Antiviral Activity and Interferon‐γ Production by Superantigen‐stimulated Lymphocytes during Normal Human Pregnancy

Abstract

PROBLEM: Plasma interferon (IFN)‐γ levels, lymphocyte responsiveness, and evaluation of the relationship between circulating antiviral activity (AA) and IFN‐γ production were studied in pregnant women and nonpregnant age‐matched controls with the objective of elucidating the downregulation of IFN‐γ production in successful pregnancy.METHOD OF STUDY: In plasma and supernatants of peripheral blood mononuclear cell (PBMC) cultures, stimulated with staphylococcal enterotoxin A (SEA) superantigen, from 43 pregnant women with a history of normal pregnancy and 30 healthy nonpregnant age‐matched controls, levels of AA were measured in a micromethod by inhibition of the cytopathic effect (CPE) caused by vesicular stomatitis virus (VSV) in the human amnionic cell line (WISH).RESULTS: Significantly higher plasma AA (60% was IFN‐γ and residual activity was acid‐labile IFN‐like) was present in pregnant women than controls. On the other hand, SEA‐activated PBMCs from pregnant women produced significantly lower IFN‐γ levels than those of nonpregnant women. Furthermore, maternal plasma AA levels correlated negatively with IFN‐γ production by SEA‐stimulated PBMCs.CONCLUSION: The hypothesis that successful pregnancy requires downregulation of IFN‐γ is only partially sustained, suggesting that the immunology of pregnancy is more complex and that murine and human pregnancy have different cytokine profiles.