Abstract
The active entity responsible for inducing interleukin-6 production by human gingival fibroblasts was partially purified by ion-exchange chromatography from the water-soluble fraction of Mycoplasma salivarium cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the final preparation revealed one densely stained band with a molecular weight of 20.6 kilodaltons and two faint bands with molecular weights of 40.5 and 82.5 kilodaltons. The specific activity of the final preparation was 34-fold higher than that of the starting water-soluble fraction. The interleukin-6-inducing activity was destroyed by proteinase K and reduced 70% by lipoprotein lipase and heat treatment, but was not affected by deoxyribonuclease I or endoglucosidase D. The final preparation induced small amounts of tumor necrosis factora and interleukin-1β in a myelomonocytic cell line, THP-1 cells, but did not induce interleukin-6. The ability of Escherichia coli lipopolysaccharide to stimulate human gingival fibroblasts to release interleukin-6 was dependent upon the presence of serum in the assay medium, but that of the final preparation from M. salivarium was not. Thus, we partially purified the protein(s) from M. salivarium which were capable of stimulating human gingival fibroblasts to release interleukin-6 by a mechanism different from that of E. coli lipopolysaccharide.
