- The aim of the study was to investigate the stimulatory effect of lipopolysaccharide (LPS) on IL-lalpha production in different compartments of term and preterm placental tissues. Homogenates from amnion, chorion, and from fetal (subchorionic placental tissues, maternal decidua, and mid-placental tissue before and after perfusion of isolated placental cotyledons of 5 term placentas and 4 placentas obtained after preterm birth (28-34 W of gestation) were examined. Isolated placental cotyledons were dually perfused LPS (100 ng/kg perfused placental tissue) was perfused into the maternal side during 10 hours. Homogenates of the samples were examined by ELISA for IL-1alpha levels, and paraffin sections of the samples were stained by immunohistochemical staining, to characterize the cellular origin of placental IL-1alpha. Paired t test and ANOVA determined statistical significance. In the homogenates, there was a tendency towards higher IL-lalpha levels in all preterm placental compartments as compared to the term compartments before perfusion. A significant increase was observed only in the chorion compartment (p = 0.035). LPS had significantly increased IL-la levels only in the decidua compartment of term placentas as compared to other placental compartments (p = 0.0004), and had decreased IL-1alpha levels in the mid-placenta (p = 0.034). In preterm placentas, addition of LPS did not affect the expression levels of IL-1alpha in either fetal or maternal compartments as determined by ELISA and immunohistochemical staining. IL-la levels in the chorion compartment of preterm placenta were significantly higher as compared to term placenta. LPS affects placental tissues of term and preterm placentas differently. Also, in the term placentas, LPS affected the different compartments differently. Thus, IL-1alpha may have a key role (as a autocrine/paracrine factor) in the regulation of normal and pathological pregnancy and parturition.