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.