Immune enhancement activities of silk lutein extract from Bombyx mori cocoons

Declining immune function poses an important clinical challenge worldwide and supplementation with natural products that possessing immune enhancing properties is a promising approach for preventing or delaying immune function decline. Cocoons from yellow silkworms are a significant source of lutein, and this unexplored silk extract could be a viable alternative source for dietary lutein. This study assessed immunomodulatory activities of the silk lutein extract. Female BALB/c mice orally received lutein, either as silk or marigold extracts (10 or 20 mg/kg daily), or vehicle only (1% tween 80 in PBS pH 7.4) for 4 weeks. Natural killer (NK) cell activity, specific antibody production, lymphocyte subpopulations, mitogen-induced lymphocyte proliferation, and cytokine production were examined.

Silk lutein extract increased NK cell activity, and the effect was dose-related whereas marigold lutein extract was ineffective. Silk lutein extract dose-dependently enhanced antibody production in pre-immunized mice but marigold lutein extract had no effect. Feeding with silk lutein extract increased the populations of CD3+ and CD4 + CD3 + cells. Silk lutein extract also stimulated concanavalin A- and lipopolysaccharide-induced proliferations of T and B lymphocytes, respectively. Moreover, silk lutein extract increased IL-2 and IFN-γ production while the effect of marigold lutein extract was undetectable.

Together, silk lutein extract enhanced both innate and adaptive immune functions. This preparation may prove to be an effective supplement for strengthened immunity.