A signiÐcant immunomodulating activity was found in the hot-watersoluble extract of an edible brown seaweed, Hijikia fusiforme (Hijiki in Japanese) which showed an enhancing activity for the proliferative response of spleen cells in endotoxin-nonresponder C3H/HeJ mice. This activity was separated into polysaccharide and nonpolysaccharide fractions. The former fraction exhibited a much higher activity than that of the latter fraction. The enhancing e †ect of the polysaccharide fraction on the proliferative response of spleen cells was associated with the response of the B cell population, but not with that of the T cell population judged by experiments using nylon wool column-puriÐed T cells and antisera against B cell-or T-cell-speciÐc antigens. The active component of the polysaccharide fraction was further fractionated using DEAE cellulose column chromatography which also caused enhancing e †ects on polyclonal antibody (IgM and IgG) production and the release of interleukin-1a or tumour necrosis factor-a from peritoneal macrophages of C3H/HeJ mice. In addition, these immunomodulating activities of the polysaccharide fraction were associated with the polysaccharides themselves, but not with the artiÐcial activities induced by contaminated endotoxins. The biochemical and physicochemical properties of the immunoenhancing polysaccharides were partially characterised and the sig-niÐcance of the present Ðnding is discussed from the viewpoint of the immunopotentiating activity of edible seaweeds against carcinogenesis.
1998 SCI.