Detection of a complement-derived chemotactic factor for tumor cells in human inflammatory and neoplastic effusions

A chemotactic factor for neoplastic cells can be generated in vitro by incubating human C5 or C5a with leukocytic or pancreatic lysosomal enzymes and is also detectable in experimental inflammatory exudates. The authors therefore sought evidence for the existence of this factor in human effusions. Using the Boyden chamber assay, they detected chemotactic activity for MB-MDA-231 human breast carcinoma cells and Walker ascites tumor cells in human inflammatory and neoplastic exudates, including ascites, pleural effusions, synovial fluids and cerebrospinal fluids. Chemotactic activity was not found in transudates, normal cerebrospinal fluid, or normal serum. Human ovarian adenocarcinoma cells from one of the effusions migrated toward autologous ascites and towards the C5-derived chemotactic factor that had been prepared in vitro. In gel filtration the chemotactic factor behaved generally as a molecule having a molecular weight of approximately 6000 daltons. The activity was blocked after incubation with antiserums directed against C5 but not by antiserums directed against C3 or C4. In vitro, chemotactic activity for tumor cells could be generated by incubating extracts of exudate cells with autologous plasma or with purified C5. The authors conclude that a chemotactic factor for tumor cells can be formed in human effusions and that this factor has properties similar to those of a previously described C5-derived chemotactic factor.