Immunomodulatory activity of polysaccharides isolated from Salicornia herbacea

Several types of immunomodulatory polysaccharides originated from plants or mushrooms have been used as immunotherapeutic agents in the treatment of cancers. Here, we describe an immunomodulatory polysaccharide that cannot only activate monocytic cells strongly, but also induce differentiation of monocytic cells into macrophages. High molecular weight substances, SHE, were isolated from Salicornia herbacea, which has been used to treat a variety of diseases including cancers in traditional oriental remedy. The immunomodulatory activities of SHE were examined on a mouse monocytic cell line, RAW 264.7 cells. We found that SHE activated RAW cells to produce cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and nitric oxide (NO) dose dependently. SHE also induced the expression of co-stimulatory molecules such as B7-1 and CD40, and increased phagocytic activity on opsonized sheep red blood cells. While increasing these parameters of macrophage activation, SHE inhibited the growth of RAW cells dose dependently inducing morphological changes from slightly adherent monocytic cells to strongly adherent macrophages. The active components of SHE appeared to be polysaccharides, and not an endotoxin. These results show that polysaccharides originated from S. herbacea possess potent immunomodulatory activity on monocyte/macrophage lineage cells.