Evidence for production of an inactive collagenase by fibroblasts from phenytoin-enlarged human gingivae.

When measured by radioimmunoassay, fibroblasts derived from the overgrown gingivae of phenytoin-treated epileptic individuals synthesize and release elevated amounts of collagenase in vitro, as compared to similar-appearing fibroblasts from normal, non-phenytoin-treated persons. However, it appears that much of the immunoreactive enzyme is unable to degrade reconstituted collagen in culture. This preliminary finding in 9 different strains of cells indicates that reduced collagenase activity by a subpopulation of cells may contribute to the development of phenytoin-induced gingival overgrowth.