Immunomodulating activity of seaweed extract on human lymphocytes in vitro

Effect of eight kinds of seaweed extract (SWE) on human lymphocytes was studied in vitro. The extracts of Hizikiafusiformis and Meristotheca papulosa (green) markedly stimulated human lymphocytes to proliferate, whereas Eucheuma muricatum and Meristotheca papulosa (red) weakly stimulated proliferation. The responder cells are T cells, because T cells purified by sheep red blood cell (SRBC) rosette-formation were significantly stimulated with SWE, but B cells were not. These extracts enhanced the induction of cytotoxic T lymphocyte (CTL) activity, but failed to enhance natural killer (NK) cell activity. These extracts had a stimulatory effect on immunoglobulin (Ig) production by B cells and tumor necrosis factor (TNF) production by monocytes. The activity of Hizikia fusiformis associated with polysaccharides which were extracted with ethanol and purified by ion-exchange and gel filtration chromatography, whose molecular weight was about 100 kDa. These results suggest that SWE has an immunomodulating activity on human lymphocytes and this ability might be useful for clinical application to treat several diseases such as tumors.