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Purified polysaccharides from cell cultures of the plant Echinacea purpurea were investigated for their ability to enhance phagocytes' activities regarding nonspecific immunity in vitro and in vivo. Macrophages (M phi) from different organ origin could be activated to produce IL-1, TNF alpha and IL-6, to produce elevated amounts of reactive oxygen intermediates and to inhibit growth of Candida albicans in vitro. Furthermore, in vivo the substances could induce increased proliferation of phagocytes in spleen and bone marrow and migration of granulocytes to the peripheral blood. These effects indeed resulted in excellent protection of mice against the consequences of lethal infections with one predominantly M phi dependent and one predominantly granulocyte dependent pathogen, Listeria monocytogenes and C. albicans, respectively. Specific immune responses to sheep red blood cells (antibody production) and to listeria (DTH) were not affected by the polysaccharides. The possibility of clinical use is discussed.

Polysaccharides purified from large-scale cell cultures of the plant Echinacea purpurea were tested for their ability to activate human phagocytes in vitro and in vivo. These substances enhanced the spontaneous motility of PMN under soft agar and increased the ability of these cells to kill staphylococci. Monocytes were activated to secrete TNF-α, IL-6 and IL-1 whereas class II expression was unaffected. Intravenous application of the polysaccharides to test subjects immediately induced a fall in the number of PMN in the peripheral blood, indicating activation of adherence to endothelial cells. This fall was followed by a leukocytosis due to an increase in the number of PMN and a lesser increase of monocytes. The appearance of stab cells and some juvenile forms and even myelocytes indicated the migration of cells from the bone marrow into the peripheral blood. The acute phase C-reactive protein (CRP) was induced, probably due to activation of monocytes and macrophages to produce IL-6. In addition a moderate acceleration of the erythrocyte sedimentation rate was observed. Altogether, as in mice, the polysaccharides could induce acute phase reactions and activation of phagocytes in humans. The possibility of clinical use is discussed.