Differential effects of fucoidans with low and high molecular weight on the viability and function of spleen cells

•The effects of fucoidans of different molecular weights on spleen cells were investigated.•High-molecular-weight fucoidan (HMF) enhances the viability and prevents the death of spleen cells.•HMF increases the production of interferon-γ and nitric oxide.•Fucoidans with different molecular weights may have different effects on the viability and function of immune cells.

Fucoidan is an edible sulfated polysaccharide purified from brown algae that has multiple biological activities. However, the effects of fucoidans of different molecular weights on immune cells have not been determined. Thus, we treated spleen cells with low- and high-molecular-weight fucoidans (LMF and HMF, respectively). Viability assays demonstrated that HMF enhanced the viability and prevented the death of spleen cells. Furthermore, functional analysis revealed that HMF significantly increased the production of interferon-γ and nitric oxide. In contrast, LMF had low activity and was relatively toxic to spleen cells. Taken together, these results indicate that HMF makes the greatest contribution to the immunostimulatory activity of fucoidan mixtures. Additionally, fucoidans with different molecular weights may have different effects on the viability and function of immune cells. This study increases our understanding of fucoidans, and may broaden their use in the basic research and clinical fields.