Immunomodulating activity of seaweed extract on human lymphocytes in vitro

Effect of eight kinds of seaweed extract (SWE) on human lymphocytes was stu died in vitro. The extracts of Hizikia fusiformis and Meristotheca papulosa (green) markedly stimulated human lymphocytes to proliferate, whereas Euch euma muricatum and Meristotheca papulosa (red) weakly stimulated proliferat ion. 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) p roduction by B cells and tumor necrosis factor (TNF) production by monocyte s. The activity of Hizikia fusiformis associated with polysaccharides which were extracted with ethanol and purified by ion-exchange and gel filtratio n chromatography, whose molecular weight was about 100 kDa. These results s uggest that SWE has an immunomodulating activity on human lymphocytes and t his ability might be useful for clinical application to treat several disea ses such as tumors. (C) 1999 International Society for Immunopharmacology. Published by Elsevier Science Ltd.