Scheme of observed effects from MWCNTs, coated with Curosurf (+CS) or without (−CS) and the proposed underlying mechanisms. Lipids and proteins of the surfactant bind to the MWCNTs and alter their surface characteristics (1.). Surfactant coated tubes are subsequently located in vesicles of MDM and free in the cytoplasm (2.). After 24 h a decrease in TNF-α release (3.) is observed which might be due to a down-regulation of the TNF-α mRNA by Curosurf compounds. An increase in ROS (5.) causes further an increase in IL-8 chemokine release in epithelial cells (5.) and induction of apoptosis (6.) in MDM. Uncoated MWCNTs which are present inside MDM after 24 h exposure, are inducing an intracellular glutathione depletion (7.).