The onset of preterm labor requires increased intrauterine prostaglandin production. Intrauterine infections are frequently associated with preterm labor and increased cytokine production. The cytokine interleukin-2 (IL-2) is a potent T-cell growth factor necessary for effective cell-mediated immunity. In this study we evaluated the effect IL-2 has on prostaglandin E2 (PGE2) biosynthesis by human chorion and decidual cells. IL-2 alone significantly stimulated decidual and chorion PGE2 production. IL-2 enhanced the stimulatory actions of interleukin-1 (IL-1), epidermal growth factor (EGF), ionomycin, and phorbol 12-myristate 13-acetate (PMA) on PGE2 production by decidual cells. Similarly, IL-2 enhanced the stimulatory actions of EGF and PMA, but not IL-1 or ionomycin, on PGE2 production by chorion cells. These data suggest that IL-2 could potentially participate in the mechanisms of preterm labor in association with intrauterine infection.