Identification of the Primary Structure of Selenium-Containing Polysaccharides Selectively Inhibiting T-Cell Proliferation

We previously described the biosynthesis, isolation, and immunosuppressive activity of the selenium-containing polysaccharide fraction isolated from the mycelial culture of Lentinula edodes. Structural studies have shown that the fraction was a protein-containing mixture of high molar mass polysaccharides alpha- and beta-glucans. However, which of the components of the complex fraction is responsible for the immunosuppressive activity non-typical for polysaccharides of fungal origin has not been explained. In the current study, we defined four-polysaccharide components of the Se-containing polysaccharide fraction determined their primary structure and examined the effect on T- and B-cell proliferation. The isolated Se-polysaccharides, alpha-1,4-glucan (M-w 2.25 x 10(6) g/mol), unbranched beta-1,6-d-glucan, unbranched beta-1,3-d-glucan and beta-1,3-branched beta-1,6-d-glucan (M-w 1.10 x 10(5) g/mol), are not typical as components of the cell wall of L. edodes. All are biologically active, but the inhibitory effect of the isolated polysaccharides on lymphocyte proliferation was weaker, though more selective than that of the crude fraction.

Automated summary

This study investigated the immunosuppressive activity of a selenium-containing polysaccharide fraction isolated from Lentinula edodes, identifying four polysaccharide components with varying levels of biological activity. While all components displayed inhibitory effects on lymphocyte proliferation, the isolated polysaccharides showed weaker but more selective activity compared to the crude fraction.