BACKGROUND:In a recent double-blind placebo-controlled crossover-study the "immune stimulatory" effects (activation of macrophages leading to enhanced phagocytosis and production of several cytokines) of Echinacea purpurea preparations (EPP) which were observed in vitro experiments and following parenteral administration could not be confirmed following oral application of the drug in healthy volunteers. The aim of the present study was to investigate whether or not oral EPP has any effect on important lymphocyte-subpopulations. SUBJECTS AND METHODS:Forty healthy male volunteers (age range 20-40 years) participated in the study. They received either a commercially available pressed juice of E. purpurea herbs or placebo juice using a double-blind placebo-controlled cross-over design with two treatment periods of 14 days. The total number of lymphocytes and 12 subgroups of lymphocytes were determined by using Flow-cytometry. RESULTS:After 1 week of treatment with verum the mean value of the total number of lymphocytes decreased slightly (-6%, p = 0.033) compared to the initial value. Treatment for 1 and 2 weeks with EPP had only minor effects on two of the 12 subtypes of lymphocytes. No significant changes were observed in the verum period for the following types of cells: T- and B-lymphocytes, CD4 + - and CD8 + -T-lymphocytes including the subgroups of "naive" and "memory" CD4 + - and CD8 + -T-lymphocytes as well as the natural killer cells. Using a modified version of the Wilcoxon-Mann-Whitney-U-test, which is claimed to be optimal for the evaluation of the results of studies with a cross-over design, a significant difference was found for the number of CD8 + -T-lymphocytes and natural killer cells corresponding to either a decrease during treatment with verum or an increase in the number of these cells in the placebo period. CONCLUSION:Oral administration of EPP for 1 and 2 weeks has only minor effects on two out of 12 lymphocyte subpopulations determined in the study. The small differences observed in the number of CD8 + -T lymphocytes and natural killer cells are only of questionable physiological relevance.

Echinacea extracts are widely used in European countries and in the United States as "immune-stimulating" agents. Even though the evidence to stimulate certain components of the nonspecific immune system (phagocytosis, macrophages, and production of cytokines) stems from in vitro experiments or studies after parenteral application, the commercially available Echinacea preparations used as drugs or supplements are for oral use. The aim of the study was to determine whether phagocytic activity and production of cytokines is stimulated by oral application of a commercially available Echinacea preparation. Forty healthy male volunteers (ages 20-40 years) participated in the study. They received either a freshly expressed juice of Echinacea purpurea herbs or placebo juice using a double-blind placebo-controlled crossover design with two treatment periods of 14 days and a wash-out period of 4 weeks in between. Endpoints for immune stimulation: phagocytic activity of polymorphonuclear leukocytes and monocytes measured by flowcytometry, production of tumor necrosis factor alpha (TNF)-alpha and Interleukin (IL)-1beta by LPS-stimulated blood monocytes. Echinacea purpurea herbs did neither enhance phagocytic activity of polymorphonuclear leukocytes nor that of monocytes when compared with placebo. Echinacea purpurea herbs did not influence the production TNF-alpha and IL-1beta by LPS-stimulated monocytes. Unexpectedly, Echinacea purpurea herbs decreased serum ferritin concentration (p = 0.0005). All other laboratory and safety data remained unchanged. The "immune stimulation" by Echinacea purpurea observed in vitro and after parenteral administration are not confirmed in healthy humans after oral intake. Other immunomodulatory effects may explain the benefits of Echinacea preparations in reducing duration and severity of upper-respiratory tract infections found in randomized, double-blind clinical trials.

We previously observed a gender difference in the cytokine response of peripheral blood monocytes (PBM). The study was performed to find out whether the gender-related difference might be due to hormonal changes during the menstrual cycle in healthy premenopausal females. The release of tumour necrosis factor α (TNF-α) was reduced in the premenopausal females during the luteal phase compared to the follicular phase. Compared to the male controls the release of TNF-α and of interleukin 6 (IL-6) during the luteal phase was also diminished. In premenopausal females the concentration of estradiol in plasma correlated with the release of TNF-α and IL-6 during the luteal phase.