Potential mechanisms of the long fibre-mediated inflammatory response. The following three potential mechanisms by which CNT cause inflammation in the pleural space were explored in this study. (A) Long fibres interact with the pleural macrophages producing cytokines that directly elicit an inflammatory response. (B) Long fibres interact directly with mesothelial cells with the subsequent factors released leading to granulocyte influx. (C) Long fibres interact with macrophages inducing the release of cytokines which stimulate the mesothelial cells, amplifying the inflammatory response. As initial results showed no response from the mesothelial cells to direct exposure to CNT, the effect of factors released from CNT-exposed mesothelial cells on macrophages was not examined.