Vaxfectin enhances antigen specific antibody titers and maintains Th1 typeimmune responses to plasmid DNA immunization

Antigen specific immune responses were characterized after intramuscular im munization of BALB/c mice with 5 antigen encoding plasmid DNAs (pDNAs) comp lexed with Vaxfectin, a cationic lipid formulation. Vaxfectin increased IgG titers for all of the antigens with no effect on the CTL responses to the 2 antigens for which CTL assays were performed. Both antigen specific IgG1 and IgG2a were increased, although IgG2a remained greater than IgG1. Furthe rmore. Vaxfectin had no effect on IFN-gamma or IL-4 production by splenocyt es re-stimulated with antigen. suggesting that the Th1 type responses typic al of intramuscular pDNA immunization were not altered. Studies with IL-6 - /- mice suggest that the antibody enhancement is IL-6 dependent and results in a correlative increase in antigen specific antibody secreting cells. (C ) 2001 Elsevier Science Ltd. All rights reserved.