POSSIBLE IMMUNOMODULATING ACTIVITIES IN AN EXTRACT OF EDIBLE BROWN ALGA, HIJIKIA FUSIFORME (HIJIKI)

A significant immunomodulating activity was found in the hot-water-sol uble extract of an edible brown seaweed, Hijikia fusiforme (Hijiki in Japanese) which showed an enhancing activity for tile proliferative re sponse of spleen cells in endotoxin-nonresponder C3H/HeJ mice. This ac tivity was separated into polysaccharide and nonpolysaccharide fractio ns. The former fraction exhibited a much higher activity than that of the latter fraction. The enhancing effect of the polysaccharide fracti on on the proliferative response of spleen cells was associated with t he response of the B cell population, but not with that of the T cell population judged by experiments using nylon wool column-purified T ce lls and antisera against B cell-or T-cell-specific antigens. The activ e component of the polysaccharide fraction was further fractionated us ing DEAE cellulose column chromatography which also caused enhancing e ffects on polyclonal antibody (IgM and IgG) production and the release of interleukin-1 alpha or tumour necrosis factor-alpha from peritonea l macrophages of C3N/HeJ mice. In addition, these immunomodulating act ivities of the polysaccharide fraction were associated with the polysa ccharides themselves, but not with the artificial activities induced b y contaminated endotoxins. The biochemical and physicochemical propert ies of the immunoenhancing polysaccharides were partially characterise d and the significance of the present finding is discussed from the vi ewpoint of the immunopotentiating activity of edible seaweeds against carcinogenesis. (C) 1998 SCI.