Acute inflammatory activity of the S100 protein CP-10. Activation of neutrophils in vivo and in vitro.

The murine S100 chemotactic protein of m.w. 10,000 termed (CP-10), has potent chemotactic activity for murine and human myeloid cells. We examined the ability of a synthetic CP-10 hinge region peptide CP-10(42-55) and rCP-10 to act as chemotactic agents and induce expression of the adhesion molecule Mac-1 (CD 11b/CD 18) in vivo. Maximal neutrophil (PMN) accumulation occurred between 2 to 8 h after mouse footpad injection of rCP-10 (10(-7) M) or CP-10 peptide (10(-6) M). The infiltrating PMN expressed high levels of Mac-1, and low levels of the murine L-selectin Mel-14. Injection of CP-10 peptide i.p. also induced infiltration of PMNs that expressed high levels of Mac-1. Cell suspensions obtained after i.p. injection of CP-10 peptide could be significantly inhibited from adhering to fibrinogen-coated plates when incubated with anti-Mac-1 antibody. The chemotactic activity of CP-10 peptide toward murine inflammatory PMN in vitro was also inhibited by anti-Mac-1 antibody. Neither CP-10 analogue stimulated or primed murine inflammatory or human blood neutrophils for superoxide production or granular enzyme release. The localization of CP-10 in vivo was examined using murine footpads injected with LPS and was found to be concentrated around the endothelial cells of the small blood vessels. This distribution suggests that the accumulated CP-10 the may contribute to the generation of a chemotactic gradient.