Studies on the action of interleukin-1 on term human fetal membranes and decidua

Recent studies have indicated the possible importance of cytokines in the onset of term and preterm labor. To examine this further, the effect of interleukin-1 beta (IL-1 beta), interleukin-1 alpha (IL-1 alpha), and interleukin-6 (IL-6) on prostaglandin output by dispersed cells from human amnion, chorion laeve, and decidua obtained at term (38-40 weeks gestation) was examined. During the first or second 24 h of culture no significant effect of these interleukins on prostaglandin output was observed. The reason for this apparent refractoriness was further investigated by studying the distribution of IL-1 receptors in frozen sections of undisrupted fetal membranes and decidua at term. Whole-tissue autoradiography indicated that receptors were present in chorion-decidua but not in amnion. By using emulsion autoradiography, IL-1 receptors were found in high concentrations in chorion laeve and were absent in amnion and at low levels in the decidua. These studies indicate that under normal circumstances in human pregnancy at term IL-1 did not stimulate prostaglandin production by dispersed cells. In the case of amnion, this may be due to the absence of receptors, and therefore it would appear that the IL-1 receptor must first be induced in this tissue before it can respond to this cytokine. Furthermore, although chorion laeve expresses the IL-1 receptor, dispersed cells from this tissue did not respond to the cytokine by increasing prostaglandin output.