Quantification of mouse macrophage chemotoxis in vitro: role of C5 for the production of chemotactic activity

Abstract

A method was developed for the quantification of mouse macrophage chemotaxis in vitro. It was found that the fifth component of complement is necessary for the production of chemotactic activity in mouse serum by inflammatory agents such as endotoxin or aggregated gamma globulin. The majority of macrophage chemotactic activity produced by these agents in mouse serum can be attributed to a low molecular weight (ca. 15,000) chemotactic factor. The data suggest that this factor is the biologically active cleavage product of the fifth component of complement, C5a. In addition to this low molecular weight factor, there is additional chemotactic activity present in normal mouse serum but not in C5 deficient serum. High molecular weight background chemotactic activity in untreated serum of other species has been previously reported but never clearly identified. The nature of this heavy molecular weight chemotactic factor(s) is not yet known, but this activity is clearly absent in C5 deficient serum and thus C5 is required for its presence.