Interleukin-8 Production by CD16−CD56bright Natural Killer Cells in the Human Early Pregnancy Decidua

Abstract

Decidual CD16−CD56bright natural killer (NK) cells were sorted from the decidual mononuclear cells (MNC) at the early pregnancy using a fluorescence activated cell sorter. 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 α and IL-1 β 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.