Potentiation of fibroblast DNA synthesis by a phenytoin-induced mononuclear cell derived factor in vitro.

Human mononuclear cells purified by Lymphoprep flotation were incubated with phenytoin (PHT) (20 micrograms/ml) or its metabolite p-HPPH (2 micrograms/ml) in the presence of Concanavalin A (10 micrograms/ml) in vitro. The results indicate that phenytoin and its metabolite p-HPPH induce the release of a mononuclear cell factor(s) that activates quiescent human gingival fibroblast to synthesize DNA.