Echinacea: Stimulation of mouse spleen cells by commercial products

Echinacea, an herbal remedy originally used by the plains Indians of North America, has gained credibility as an immunostimulator, used especially for the treatment of incipient colds and "flu". We examined the effect of over-the- counter preparations of Echinacea, on mouse spleen cells in vitro. All products were diluted to provide equivalent amounts of Echinacea, based on the suggested product dose. We measured the effect on proliferation of BALB/c spleen cells and on production of IgM, IgG sub-classes, and IgA by the cultured cells. Of the 6 products tested, #1 (an extract in glycerol) showed a 10 fold stimulation of spleen cell proliferation, the same company's extract in alcohol (#2) showed an 8 fold stimulation, but the other companies' products (#s 3-6) showed from no effect to a maximum of 4 fold stimulation. With respect to immunoglobulin production, product #1 increased IgM production from 2 μg/ml in unstimulated cells to 18 μg/ml. None of the other products increased IgM production to above 4 μg/ml. IgG subclass production was stimulated to a different extent, depending on the subclass. IgA production was increased from 0.2 μg/ml to 3.4 μ/ml by product #1. We also prepared our own Echinacea extract and it showed stimulatory properties similar to those of commercial product #1. Preliminary results with human spleen cells paralleled those with mouse spleen cells. Our studies confirm that Echinacea extracts stimulate immune system cells, but as there was great discordance in the effects of the commercial preparations, our results support the necessity for increased regulation of herbal products.