Stumbled on the following while googling around. Sounds like Arabinoglactan is a serious immune system stimulant and might be behind the Echinacea testamonies.
RO

In May of 1989, the Journal of the National Cancer Institute published an article entitled “Macrophage Activation by the Polysaccharide Arabinogalactan Isolated from Plant Cell Cultures of Echinacea purpurea.” The purpose of this study was to determine if arabinogalactan - a chemical component of Echinacea purpurea - stimulates macrophages. Macrophages are important cells of the immune system which kill foreign cells and cancer cells. In this experiment male and female mice 6-8 weeks old were injected with acidic arabinogalactan from cell cultures of Echinacea purpurea. This polysaccharide was administered in doses ranging from 4 mg/kg to 4 g/kg. The mice were then exposed to tumor-cells and microorganisms called Leishmania enriettii. The results of the treatment showed that arabinogalactan induced macrophages to produce tumor necrosis factor (TNF) — a tumor inhibiting factor in the blood of animals. This resulted in the macrophage cells being 25% more effective in killing cancer cells when compared to control groups. Against Leishmania enriettii, administration of arabinogalactan proved to make macrophages more effective in killing microorganisms through the release of 40% more H-thymidine than control macrophages. This experiment demonstrated that Echinacea purpurea is effective in activating macrophages to fight off infections and cancer cells (Luettig et al. 669-675).

The results of the previous of experiment were reinforced by an article published in the July 1997 issue of the International Journal of Immunopharmacology entitled “Echinacea-induced Cytokine Production by Human Macrophages.” Commercial preparations of Echinacea juice and dried juice were administered to human macrophages in vitro in doses ranging from 10 micrograms/milliliter to 0.012 microgram/milliliter. Macrophages cultured in Echinacea purpurea showed significantly higher levels of IL-6, IL-10, IL-10, and TNF when compared to unstimulated cells. The production of these chemicals is consistent with the immune system’s response against foreign substances. This experiment helps to prove that Echinacea purpurea helps to boost the immune system (Burger et al. 371-9).

In 1995, the Journal of Alternate Complement Medicine published an article called “Results of Five Randomized Studies on the Immunomodulatory Activity of Preparations of Echinacea.” Together these five studies tested 134 (18 female and 226 male) healthy volunteers between the ages of 18 and 40. Studies 1 and 2 tested intravenous homeopathic complex preparations containing Echinacea angustifolio D1 and D4, respectively. Studies 3, 4, and 5 tested oral alcoholic extracts from two types of Echinacea roots: Echinacea purpurea and Echinacea pallida. In studies 1-4 subjects were on the Echinacea regimen for 5 consecutive days, while in study 5 patients were on the regimen for 4 consecutive days. The primary outcome of the five studies was activation of the immune system through increased phagocytic activity. Phagocytic activity is important because phagocytes protect the body by consuming foreign cells. The secondary outcome was to increase the number of leukocytes (white blood cells) in the blood. The results of studies 1 and 2 showed increased phagocytic activity when compared to the placebo: 22.7% and 54%, respectively. Studies 3, 4, and 5 showed no significant increase in phagocytic activity and none of the studies showed any effect on leukocyte numbers. This study thus concluded that Echinacea angustifolio had significant effects on boosting the immune system when administered for 5 consecutive days (Melchart et al. 145-60).

In January of 1997, Immunopharmacology published an article entitled “In Vitro Effects of Echinacea and Ginseng on Natural Killer and Antibody-Dependent Cell Cytotoxicity in Healthy Subjects and Chronic Fatigue Syndrome or Acquired Immunodeficiency Syndrome Patients.” In this study Echinacea purpurea was tested for its ability to increase immune function through enhancement of natural killer cells in normal individuals and those suffering from either chronic fatigue or AIDS. Natural killer cells are a type of white blood cell that release lethal chemicals when bound to tumor cells and infected body cells. They are thought to play an important roll in cancer prevention by preventing and killing abnormal cells (http://www.graylab.ac.uk/omd/index.html). Natural killer cells were isolated using a Ficoll-gradient and put in the presence of Echinacea. Doses of Echinacea greater than 0.1 microgram/kilogram showed significant enhancement of natural killer cells. This study gives further evidence that Echinacea enhances the immune system (Broumand et al. 229-35). It should be noted that most physicians do not recommend Echinacea for the treatment of AIDS (Mack 237).