Modification of lily polysaccharide by selenylation and the immune-enhancing activity

• Nine selenizing lily polysaccharides, sLP1–sLP9, were prepared.
• sLPs’ immune-enhancing activities were compared taking unmodified LP as control.
• Selenylation modification can significantly enhance LP's immune-enhancing activity.
• sLP6 presents the best effect and can be as a new polysaccharide immunopotentiator.

Lily polysaccharide (LP) was extracted, purified and selenizingly modified by HNO3–Na2SeO3 method according to L9(34) orthogonal design. Nine selenizing LPs, sLP1–sLP9, were obtained and their immune-enhancing activities were compared taking unmodified LP as control. The results in vitro test showed that sLP6 presented the strongest activity in promoting lymphocytes proliferation in single and synergetic with PHA, and the relative expression level of IL-2, IL-6 and IFN-γ mRNA of chicken peripheral lymphocytes. The results in vivo test showed that sLP6 could promote lymphocytes proliferation and enhance the serum antibody titers and serum IL-2, IL-6, IFN-γ contents more significantly than LP in chickens vaccinated with Newcastle Disease (ND) vaccine. These results indicate that polysaccharide selenizing can significantly enhance the immune-enhancing activity of LP and the optimal modification conditions are 400 mg of Na2SeO3 per 500 mg of LP, the reaction temperature of 70  °C and the reaction time of 6 h.