Interleukin-8 production by CD16-CD56bright natural killer cells in the human early pregnancy decidua

Decidual CD16-CD56bright natural killer (NK) cells were sorted from the decidual mononuclear cells (MNC) at the early pregnancy using a fluorescence activated cell sortor. The CD16-CD56bright NK cell population occupies a major population in the decidual MNC, in contrast to a very small population (< 1%) in the peripheral blood MNC. These decidual CD16-CD56bright NK cells produced a large amount of IL-8, i. e., mean of 96.7 +/- 19.8 ng/ml in the 24 hr-cultured supernatants without any stimulant, which was comparable to the IL-8 production by LPS-stimulated peripheral blood MNC. Most of the IL-8 was ascribable to the production from decidual CD16-CD56bright NK cells. Intracytoplasmic IL-8 in the decidual CD56bright NK cells was also detected by flow cytometry. RT-PCR methods confirmed IL-8 mRNA expression in this population, while no or very scarce expression of IL-1 alpha and IL-1 beta mRNA was observed. The present study is a first observation revealing that decidual CD16-CD56bright NK cells express IL-8 mRNA and produce IL-8.