ArticleOrr W, Phan SH, Varani J, Ward PA, Kreutzer DL, Webster RO, Henson PM.
Proc Natl Acad Sci U S A. 1979 Apr;76(4):1986-9.
Previously, we have stablished that the fifth component of complement (C5) serves as an important source of mediators that have locomotory (chemotactic) activity for leukocytes and tumor cells. C5a, a fragment (Mr 11,200) derived from the NH2-terminal portion of the alpha chain of C5, is the major chemotactic peptide for leukocytes. The present studies demonstrate that cleavage of C5a with trypsin generates a derivative peptide that is chemotactic for tumor cells (Walker carcinosarcoma). This fragment has an estimated Mr 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. These studies emphasize the key role of the C5a region of the C5 molecule in the generation of peptides that affect locomotory responses of cells.