Oral administration with chitosan hydrolytic products modulates mitogen-induced and antigen-specific immune responses in BALB/c mice.

The aim of this study was to investigate whether oral administration in BALB/c mice with chitosan hydrolytic products including chitosan hydrolysate, LMWC and a chitooligosaccharide mixture (oligomixture), modulates mitogen-induced and antigen-specific immune responses. A water-soluble chitosan hydrolysate was obtained via cellulase degradation of chitosan, and a LMWC and the oligomixture were separated from this hydrolysate. In non-immunized mice, both the chitosan hydrolysate and oligomixture significantly increased the phagocytic activity of peritoneal macrophages. Three chitosan hydrolytic products significantly increased the mitogen-induced proliferation of splenocytes and Peyer's patch (PP) lymphocytes. LMWC and oligomixture up-regulated IFN-γ secretion, and induced predominantly Th1 cytokine secretion in splenocytes. In antigen-specific immunity, similar effects of the chitosan hydrolytic products were observed on augmenting ovalbumin (OVA)-, as well as mitogen-, induced proliferation of splenocytes harvested from OVA-immunized mice. Interestingly, oligomixture was the most potent chitosan hydrolytic product to elicit OVA-specific IgM, IgG, and IgA production, while LMWC was the most potent one to elevate splenic IFN-γ production and IFN-γ/IL-4 (Th1/Th2) ratio. These results provide the distinct immunomodulatory properties of chitosan hydrolytic products in response to mitogens and specific antigen, paving the way for further development and application of dietary chitosan hydrolytic products against immune disorders and infection.