Preparation of chitosan hydrochloride stabilized emulsion and its immunostimulatory effect

Abstract:

In order to increase the ability of oil-emulsion adjuvant to stimulate cellular immunity, chitosan hydrochloride with positive charge was selected to stabilize oil-in-water emulsion (CHE). In this paper, model antigen ovalbumin was selected to prepare vaccines with emulsion adjuvant, commercial adjuvant or no adjuvant. The emulsion was characterized by measuring the particle size, electric potential and antigen adsorption rate. BALB/c mice were immunized by intramuscular injection. Serum antibody levels, the numbers of IL-4-secreting cells in splenocytes, cytotoxic T lymphocyte (CTL) response, and the expression of central memory T cells were measured to evaluate the immunostimulatory effect. The results showed that chitosan hydrochloride can effectively stabilize the emulsion. The emulsion size is about 600 nm, and the antigen adsorption rate is more than 90%. After immunization, CHE could increase serum antibodies levels and increase IL-4 secretion. Expression of CTL surface activation molecules was also increased to stimulate CTL response further and to increase the CD44⁺CD62L⁺ in T cells proportion. CHE as adjuvant can stimulate humoral and cellular immunity more efficiently, and is expected to extend the duration of protection.