Interaction of the terminal complement components C5b-9 with synovial fibroblasts: binding to the membrane surface leads to increased levels in collagenase-specific mRNA.

The late complement components, apart from their lytic function, are known to trigger the release of various proinflammatory substances from different types of nucleated cells. In the present study, the interaction of C5b-9 with synovial fibroblast cells (SFC) was examined. It was found that incubation of SFC with activated complement components resulted in binding of C5b-9 to the cell membrane; subsequently an increase in abundance of collagenase-specific mRNA was seen, as assessed by Northern blotting. When C8-deficient serum was used as source of complement neither binding of C5b-9 nor an increase in collagenase-specific mRNA could be detected. These findings suggest that C5b-9, which might be generated during rheumatoid inflammation, may contribute to chronic joint destruction by triggering collagenolytic activity.