Cytokines such as monocyte chemotactic peptide-1 (MCP-1), interleukin-8 (IL-8), 
RANTES (Regulated on Activation and Normally T-cells Expressed and presumably 
Secreted) and interleukin-10 (IL-10) are thought to play pivotal roles in immune 
recognition, acceptance of the fetal allograft, maintenance of pregnancy and 
parturition. Their secretion and regulation within the third trimester uterus 
is, however, less well defined. We therefore investigated the release of these 
cytokines by third trimester amnion, chorion, placenta and decidua, and studied 
the influence of prostaglandin E2 (PGE2) infusion on their release in a dynamic 
placental cotyledon perfusion system. MCP-1 was released predominately by the 
chorion (78.2 +/- 7.3 pg/mg wet tissue weight; mean +/- SEM), decidua (112.4 +/- 
5.2 pg/mg) and placenta (101.8 +/- 5.0 pg/mg) with low amounts from the amnion 
(1.3 +/- 0.4 pg/mg). High concentrations of IL-8 were released by the amnion 
(39.9 +/- 5.3 pg/mg), chorion (52.8 +/- 1.9 pg/mg), decidua (42.2 +/- 1.5 pg/mg) 
and placenta (45 +/- 1.3 pg/mg). Release of RANTES was not detectable from the 
amnion but was detected in moderate amounts from the chorion (6.0 +/- 1.2 
pg/mg), decidua (15.2 +/- 1.4 pg/mg) and placenta (26.9 +/- 1.6 pg/mg). Low 
concentrations of IL-10 were secreted by the chorion (6.8 +/- 0.8 pg/mg), 
decidua (9.0 +/- 0.9 pg/mg) and placenta (3.3 +/- 0.3 pg/mg) with none 
detectable from the amnion. MCP-1, IL-8, RANTES and IL-10 were all released by 
perfused placental cotyledons. PGE2 stimulated release of MCP-1, IL-8 and IL-10 
into the maternal and of MCP-1 and IL-8 into the fetal circulation of the 
placenta but had no effect on RANTES release. It is suggested that MCP-1 and 
IL-8 may be involved in the inflammatory process of parturition and IL-10 in the 
protection of the fetal allograft. In addition, PGE2 may have an important 
immunomodulatory role within the uterus at term.