Amaranthus spinosus water extract directly stimulates proliferation of B lymphocytes in vitro

Amaranthus spinosus Linn. (thorny amaranth), a plant that grows in the wild fields of Taiwan, is extensively used in Chinese traditional medicine to treat diabetes. There have been no published studies on the immunological effects of A. spinosus. To determine whether A. spinosus has immuno-modulatory effects and clarify which types of immune effector cells are stimulated in vitro, we investigated the stimulatory effect of wild A. spinosus water extract (WASWE) on spleen cells from female BALB/c mice. We found that WASWE significantly stimulated splenocyte proliferation. However, isolated B lymphocytes, but not T lymphocytes, could be stimulated by WASWE in a dose response manner. After sequentially purifying WASWE, a novel immuno-stimulating protein (GF1) with a molecular weight of 313 kDa was obtained. The immuno-stimulating activity of the purified protein (GF1) was 309 times higher than that of WASWE. These results indicate that WASWE does indeed exhibit immuno-stimulating activity via directly stimulating B lymphocyte activation in vitro. Further, these results suggest that the immuno-stimulating effects of WASWE might lead to B lymphocyte activation and subsequent T cell proliferation in vitro. These results are potentially valuable for future nutraceutical and immuno-pharmacological use of WASWE or its purified fractions.