Cytokines that use gp130 as a signal transducer stimulate mouse placental lactogen-I (mPL-I) but inhibit mPL-II production in vitro. 
Interleukin-11 (IL-11), leukemia inhibitory factor (LIF), and oncostatin M (OM), all of which use gp130 as a signal transducer, significantly inhibited mouse placental lactogen-II (mPL-II) secretion by cultured placental cells from Days 7, 9, and 12 of pregnancy.  These cytokines significantly stimulated mPL-I secretion by cells from Day 9, but not Day 7, of pregnancy.  An antibody to LIF completely blocked the stimulatory and inhibitory effects of LIF on mPL-I and mPL-II secretion, respectively.  LIF and OM decreased the abundance of mPL-II mRNA in placental cells.  Double immunocytochemistry for mPL-I and mPL-II indicated that LIF, OM, and IL-11 significantly increased the number of giant cells containing only mPL-I or both mPL-I and mPL-II but decreased the number of giant cells containing only mPL-II.  IL-6, which also uses gp130 as a signal transducer, inhibits mPL-II secretion only after midpregnancy; however, addition of soluble IL-6 receptor (sIL-6R) together with IL-6 resulted in a significant inhibition of mPL-II secretion before midpregnancy.  Treatment of cells from Day 12 of pregnancy with IL-6 during the first 2 days of culture resulted in significant inhibition of mPL-II secretion by the third day of culture.(ABSTRACT TRUNCATED AT 250 WORDS)