Interleukin-6 production by human gingival fibroblasts.

The ability of human gingival fibroblasts to synthesize interleukin-6 (IL-6) was studied using in vitro and immunohistochemical techniques. Culture supernatants of human gingival fibroblasts contained significant quantities of IL-6 activity which could be stimulated by fetal calf serum, recombinant interleukin-1 beta and lipopolysaccharide. The activity in the supernatants was specifically attributed to IL-6 since up to 97% of the activity could be inhibited by an anti-IL-6 antibody. Immunohistochemical studies on low-density human gingival fibroblast cultures indicated that the cells were associated with material reactive to the anti-IL-6 antibody. This localization was seen on the cell surface and in the cytoplasm of the cells. Immunoreactivity towards IL-6 was also noted in sections of human gingivae. Moderate staining was seen in the connective tissues and lower portions of the gingival epithelium, while intense staining was seen at foci of inflammation. The identification of IL-6 with human gingival tissues and cells implicates this lymphokine in the molecular events associated with the inflammatory periodontal diseases.