ABSTRACT
The term cytokines was assigned to agents released by one cell population; they react with specific antigens, and then act as intracellular mediators, as in the generation of an immune response. Endothelins and nitric oxide can be considered cytokines, as both are produced by immune cells in addition to various other cell types. Growth factors and cytokines have been implicated as mediators/modulators of steroid hormone actions on various uterine functions. Numerous studies have demonstrated that prostaglandins (PG) play critical roles in the mechanisms that regulate uterine contractions. Concentration of PGs in the amniotic fluid is elevated during labor at term. The role of various cytofactors in the control of uterine contractility appears to be both indirect and direct. It is possible that several of these agents may stimulate or inhibit uterine contractions at term and modulate labor.
