Pleural Macrophages can Promote or Inhibit Apoptosis of Malignant Cells via Humoral Mediators Depending on Intracellular Signaling Pathways.

Macrophages in malignant pleural effusions (MPEs) demonstrate a promalignant phenotype. They release mediators, which are a source of inflammation within the pleura. We established in vitro model proving that pleural macrophages isolated from effusions affect cancer cells in their pro- or anti-apoptotic activity via humoral mediators. Additionally, we measured concentrations of selected transcription factors in cancer cells. Pleural macrophages can affect the apoptosis of cancer cells via intercellular mediators which trigger different signal transductors in cancer cells. The observed effect is connected to the composition of exudate which may vary depending on its origin, either malignant or nonmalignant.