Endotoxin-induced TNF-alpha production changes inversely to its plasma level during pregnancy.

Objective: To study plasma TNF-alpha levels during normal pregnancy and the ex vivo endotoxin-induced TNF-alpha production of peripheral blood cells.

Study Design: In a longitudinal prospective study the ex vivo endotoxin-induced TNF-alpha production of peripheral blood cells and the plasma level of TNF-alpha in 18 women with uncomplicated pregnancies were determined at the 8th, 17th, 27th and 36th weeks of their pregnancy and 48 h and 6 weeks post-delivery. TNF-alpha levels were determined by ELISA technique. Data were analysed by Student's unpaired t-test.

Results: From the second trimester LPS-induced TNF-alpha production increased significantly (P<0.05) compared to non-pregnant values. In contrast, spontaneous TNF-alpha levels decreased with gestational age. Lowest values of plasma TNF-alpha levels and highest values of ex vivo endotoxin-induced TNF-alpha levels were detected at the 27th and 36th gestational weeks, respectively. Both parameters returned to non-pregnant levels after 6 weeks of delivery.

Conclusion: Gestational age influences TNF-alpha production during normal pregnancy. The observed elevation of inducible TNF-alpha production may contribute to the immune defence of the mother against infections.