Multinucleation of macrophages with water-solubilized lignin derivatives in vitro.

When macrophages derived from bone marrow were incubated with lignin derivative at 10 micrograms/ml, they formed multinucleated giant cells containing more than sixty nuclei. Cine-microscopic observation revealed that the formation of the giant cells was due to cell fusion. This phenomenon was specific for primary-cultured macrophages, and was not observed with either a macrophage cell line or established cell lines derived from other tissues.