Protective effect of chitooligosaccharides against cyclophosphamide-induced immunosuppression in mice.

Chitooligosaccharides (COS) display a variety of important biological activities, including antimicrobial, antitumor, anti-inflammatory, and immunoenhancing. In the present study, a COS sample (degree of polymerization 4-11, analyzed by FTIR and MALDI-TOF-MS) prepared by hydrolysis with a recombinant chitosanase was orally administered to mice for evaluation of its effect on cyclophosphamide (Cy)-induced immunosuppression. Thymus and spleen indices, delayed-type hypersensitivity (DTH) reaction, macrophage phagocytosis, and certain enzyme activities were significantly higher in mice treated with COS+Cy than in mice treated with Cy alone. ELISA experiments showed that COS treatment enhanced production of the cytokines IL-2, IL-12, and IFN-γ but decreased production of IL-10 in sera of Cy-treated mice. The well-defined COS product studied displayed strong immunoenhancing activity and a protective effect against Cy-induced immunosuppression. COS-derived products should be further investigated for possible immunostimulatory applications in the food and pharmaceutical industries.