Chemotactic factor for tumor cells derived from the C5a fragment of complement component C5.

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Abstract
The 5th component of complement (C5) serves as an important source of mediators that have locomotory (chemotactic) activity for leukocytes and tumor cells. C5a, a fragment (MW 11,200) derived from the NH2-terminal portion of the .alpha. chain of C5, is the major chemotactic peptide for leukocytes. Cleavage of [human] C5a with trypsin generates a derivative peptide that is chemotactic for tumor cells (Walker [rat] carcinosarcoma). This fragment has an estimated MW of 6000 as assessed by gel filtration and does not require the COOH-terminal arginine of C5a, because equivalent amounts of chemotactic activity for tumor cells can be generated from des-Arg-C5a by digestion with trypsin. The C5a-derived chemotactic peptide for tumor cells demonstrates peak activity at approximately 1 pM. The key role of the C5a region of the C5 molecule in the generation of peptides that affect locomotory responses of cells is emphasized.