Mechanism of activation of XXXX peripheral blood NK cells at the single cell level by Echinacea water soluble extracts: recruitment of lymphocyte-target conjugates and killer cells and activation of programming for lysis.

@entity1 @entity137 @entity2940 @entity4071 @entity1729 @entity7986
Echinacea purpurea, a plant originally used by native Americans to treat @entity1729 , has also been shown to exert immunomodulatory activities both in vivo and in vitro. However, the mechanism underlying Echinacea-induced immunomodulation remains largely unknown. This study examined in vitro the effects of soluble extracts of E. purpurea on natural killer (NK) cells present in @entity1 peripheral blood mononuclear cells (PBMC). Flow cytometric methods were used to examine activation, @entity137 , NK-target binding, and killer cell frequency. Treatment of PBMC with Echinacea overnight resulted in the activation of @entity7986 expression and increase in mean fluorescence intensity in both the @entity4071 + and @entity4071 + @entity2940 + NK subsets. However, the frequency of @entity4071 + cells was decreased as well as the mean fluorescence intensity was down-regulated. NK @entity137 was augmented 100% at the concentration of 0.1 microg/ml of Echinacea in a short time (4-h) assay. Examination at the single cell level revealed augmentation of the frequency of @entity2940 + NK-target conjugates and a plateau was reached after 30-60 min of incubation. Likewise, the frequency of @entity2940 + killer cells in the conjugates was also significantly increased by Echinacea. There was recruitment of non-conjugated @entity2940 + cells into @entity4071 + NK-target conjugates and activation of the NK-target non-killer conjugates into killer cells. These findings demonstrate that Echinacea extracts are potent activators of NK @entity137 . Echinacea augments the frequency of NK target conjugates and activates the programming for lysis of NK cells.
