Macrophage activation and induction of macrophage cytotoxicity by purified polysaccharide fractions from the plant Echinacea purpurea.

Purified polysaccharides (EPS) prepared from the plant Echinacea purpurea are shown to strongly activate macrophages. Macrophages activated with these substances develop pronounced extracellular cytotoxicity against tumor targets. The activation is brought about by EPS alone and is independent of any cooperative effect with lymphocytes. Also the production and secretion of oxygen radicals and interleukin 1 by macrophages is increased after activation with EPS. Cells of the macrophages lineage seem to be the main target for the action of these polysaccharides. EPS has no effect on T lymphocytes. B lymphocytes show a comparatively modest proliferation after incubation with E. purpurea EPS. Thus, these compounds, which are at least in tissue culture completely nontoxic, may be suited to activate in vivo cells of the macrophage system to cytotoxicity. They may therefore be of relevance in tumor and infectious systems.