Further studies on the C5-derived chemotactic factor for tumor cells

A factor has been studied that is chemotactic in vitro for Walker carcinosarcoma and Novikoff hepatoma cells of rats and for murine mastocytoma cells, but not for neutrophils. This chemotactic factor is generated by the incubation of normal serum with a crude extract from tumor cells. The generation of the tumor cell chemotactic factor is time and temperature dependent and results in greater than 30% reduction of serum complement activity. The tumor cell chemotatic factor appears to be a small cleavage product of the fifth complement component (C5) which binds to serum globulin. This has been shown by the use of agammaglobulinemic serum. By the use of isolated C5 fragments there is direct evidence that the tumor cell chemotactic factor is structurally derived from a larger C5 leukotactic fragment. The study of tumor cell chemotaxis, particularly the involvement of the complement system in this phenomenon, may suggest a novel approach to the investigation of the mechanism of metastasis in the malignant process.