Production of chemotactic factors for neutrophils following the interaction of Bacteroides gingivalis with purified C5.

Abstract

The aim of this study was to determine whether complement‐derived chemotactic factors are produced following the interaction of B. gingivalis with purified C5 protein. B. gingivalis strain ATCC 33277 was incubated with purified human C5 under anaerobic conditions; assay of the supernatants by SDS‐PAGE demonstrated proteolysis of C5 protein and functional hemolytic assay demonstrated inactivation of C5 activity. Supernatants were then tested for chemotactic activity for PMN's in the modified Boyden chamber, and for the presence of C5a des Arg by specific radioimmunoassay. It was noted that increased bacterial concentrations produced increased concentrations of immunoreactive C5a des Arg, and that PMN chemotactic activity was observed in the reaction mixtures. In contrast, the non‐proteolylic pathogen Actinobacillus actinomycetemcomitans Y4 failed to cleave C5 or to generate chemotactic activity from C5. When C5 was incubated with B. gingivalis under conditions resulting in maximal generation of chemotactic activity and supernatants were reacted with IgG fractions of goat anti‐C5, chemotaxis was inhibited; similar treatment of FMLP with a‐C5 failed to inhibit FMLP‐induced chemotaxis. Therefore, B. gingivalis is capable of producing C5 derived chemotactic activity by direct interaction with purified C5.