Differential distribution of interleukin-1 alpha and interleukin-1 beta proteins in human placentas.

Interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta) were identified in samples of first trimester and term placentas by immunocytochemistry using two sets of polyclonal antibodies to recombinant IL-1. All samples contained the two species of IL-1, which predominated in different types of cells: IL-1 alpha was contained primarily in placental villous trophoblastic and stromal cells whereas IL-1 beta was localized to cells in fetal and maternal blood. With respect to the cellular localization of the two proteins, early and late gestation tissues were similar. Although these results were generally consistent for the two sets of antibodies, differences were noted in the binding patterns of the individual reagents. The findings in this study provide strong support for the postulate that IL-1 modulates placental development and suggest that IL-1 alpha may be the preferred species in extraembryonic tissues.