Labor in women is associated with increased amniotic fluid prostaglandin (PG) concentrations. AF of women with term and preterm labor also contains elevated concentrations of arachidonic acid metabolites from the lipoxygenase pathway including 5-hydroxyeicosatetraenoic acid (5-HETE). We and others have shown that 5-HETE production within the uterus is increased by inflammatory cytokines. The purpose of this study was to determine whether 5-HETE production is regulated by immunotherapeutic agents that inhibit prostaglandin E2 (PGE2) production, such as interleukin-10 (IL-10) and cyclosporin A (CsA). Cultured confluent amnion cells were incubated for 16 hr with IL-10 (1 100 ng/ml), CsA (1 1000 ng/ml), or controls. Additional incubation of IL-10 and CsA (both at 10 and 100 ng/ml) were conducted on amnion cells in the presence and absence of interleukin-1 beta at 1 ng/ml. 5-HETE was measured by radioimmunoassay and cellular protein determined. IL-1 beta stimulated amnion cell 5-HETE production as expected. However, 5-HETE production by amnion cells was significantly inhibited by incubation with IL-10 and CsA, and both significantly attenuated 5-HETE production in response to IL-1 beta. We speculate that the inhibitory effect of IL-10 and CsA on amnion cell 5-HETE production is at the level of substrate release or inhibition of 5-lipoxygenase and that the use of these agents during pregnancy may not adversely affect pregnancy outcomes.