Figure 3.

STBM interact with monocytes, but phagocytosis is not required for their stimulatory properties. PKH-26-labeled STBM-NP (300 μg/ml) were incubated with monocytes for 16 h and analyzed by flow cytometry or fluorescence microscopy. (A) Representative histograms of CD14-positive monocytes read in the FL1 (CD14) and FL2 (PKH-26) channels. (B) Fluorescence microscopy of CSFE-stained monocytes (green) incubated with PKH-labeled STBM (red). DAPI (blue) was used as a nuclear counterstain. (C) Monocytes were pre-treated with various concentrations of cytochalasin B in DMSO or with DMSO alone, prior to the addition of 300 μg/ml STBM. The levels of IL-8 and IL-6 secreted by the cells after 16 h of incubation are expressed as a percentage of the amounts produced by cells stimulated with STBM in the absence of the inhibitor, which was set at 100%. Data represent mean ± SEM of three different co-cultures with STBM-NP prepared from three placentas. There was no statistical difference between cytokine secretion in the absence or in the presence of cytochalasin B.