Cationic lipid DC-Chol induces an improved and balanced immunity able to overcome the unresponsiveness to the hepatitis B vaccine

Th1 and Th2 immune responses against antigens can be modulated by the use o f adjuvants. Since antibody isotypes (IgG1 and IgG2a) and cytokines induced may reflect the Th differentiation taking place during the immune response , the humoral and cellular immune responses induced in mice against hepatit is B virus surface antigen (HBsAg) were examined when the antigen was eithe r adsorbed to aluminum hydroxyde or administered with a new adjuvant the ca tionic lipid 3 beta-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol(DC- Chol). The use of DC-Chol increased antibody responses in responding BALB/ c mice, induced more consistent IgG1 and IgG2a antibody responses in OF1 mi ce and overcame the nonresponse to HBsAg in B10.M mice. Furthermore, DC-Cho l was able to induce cellular immune responses to HBsAg. The DC-Chol induce d a balanced Th1/Th2 response, which enabled mice to overcome the inherited unresponsiveness to HBsAg encountered with aluminum-adjuvanted vaccine. Th us, the DC-Chol provides a signal to switch on both Th1 and Th2 responses, which may have important implications for vaccination against hepatitis B v irus, as well as for enhancing weak immunogenicity of other recombinant pur ified antigens in a nonresponder population. (C) 1999 Elsevier Science Ltd. All rights reserved.