Imupret modulates the innate and adaptive immune system parameters in vitro

Imupret is an alcoholic-aqueous extract of seven different herbal drugs. It is used for the treatment of recurrent infections of the respiratory tract, especially tonsillitis. We hypothesized that immunostimulatory actions of Imupret correlate with its clinical effects. The aim of the study was the assessment of the influence of Imupret on immune parameters in vitro, i.e. by analysing possible in vitro effects of Imupret on immune cells from healthy subjects.

The effect of Imupret on the phagocytotic activity of macrophages and polymorphonuclear granulocytes was determined by the quantitative determination of leukocyte phagocytosis in whole blood. Imupret did not affect the phagocyte activity of granulocytes or monocytes. The effect of Imupret on the oxidative burst was determined by measuring the production of reactive oxidants in macrophages and polymorphonuclear granulocytes in whole blood. Imupret stimulated the oxidative burst of fMLP primed phagocytes at a concentration of 5–100µg/ml. Possible cytokine modulating effects of Imupret were analysed in in vitro stimulated human peripheral blood mononuclear cells. Low concentrations of Imupret (0.001–1µg/ml) increased the IL-6 and TNF secretion and decreased IL-10 secretion of LPS-stimulated monocytes. Furthermore, IFNγ and GM-CSF secretion of CD3/CD28-stimulated T-cells was increased by Imupret in a similar concentration range (0.001–1µg/ml). At concentrations of 0.2–100µg/ml, Imupret increased IL-6 secretion of CD3/CD28-stimulated T-cells. Finally the effect of Imupret on T-cell surface marker CD4, CD8, CD25 and CD69 were determined in whole blood. High concentrations of Imupret increased the number CD25+ T-cells.

Altogether, we detected effects of Imupret on different characteristic parameters of the innate and adaptive immune system. Interestingly, we found different effects for a high and a low concentration range of Imupret. This reflects the different recommendation for the use of Imupret, i.e. higher doses for acute infections and lower doses for improving the immune status. A clinical study is planned to corroborate these findings in human volunteers.