Fibroblasts Derived From Tissue Explants of Dilantin-Induced Gingival Hyperplasia and Idiopathic Gingival Fibromatosis Show Distinct Disparity in Proliferative Responsiveness to Epidermal Growth Facto

Human gingival fibroblasts derived from tissue explants of two patients with dilantin-induced gingival hyperplasia (DGH) and one patient with idiopathic gingival fibromatosis (GF) were studied with respect to the effect of epidermal growth factor (EGF) on the proliferative characteristics of these cells. Immunohistochemical stain-ing showed that there were more EGF receptor-positive cells among DGH fibroblasts than among either normal gingival fibroblasts (NG) or GF cells. Furthermore, EGF binding studies showed that, in spite of there being no disparity in binding affinity among all these cells, DGH fibroblasts possessed approximately two-fold more EGF receptors than either NG or GF cells. In addition, the growth-promoting effect of exogenously added EGF was concentration-dependent in DGH fibroblasts but was not in either NG or GF cells. All of the above findings clearly demonstrate that DGH and GF fibroblasts exhibit distinct disparity in proliferative responsiveness to EGF and suggest that different mechanisms may be involved in the pathogenesis of these two forms of gingival hyperplasia. These observations also suggest a possible therapeu-tic approach for blocking EGF-induced cell proliferation in DGH.