Immunostimulatory DNA prepriming: A novel approach for prolonged Th1-biased immunity

Immunostimulatory DNA sequences (ISS) have been shown to promote CTL and Th 1 immune responses to coinjected antigens. This phenomenon can be attribute d to the capacity of ISS to induce the secretion of type-1 cytokines and to up regulate costimulatory ligands on antigen-presenting cells. We hypothes ized that ISS administration prior to antigen administration (prepriming), via the mechanisms stated above, would Th1 bias immune responses to subsequ ently injected antigens for an extended period of time. The data presented show that ISS provide in vivo adjuvant activity for up to 2 weeks after int radermal or intranasal delivery. Furthermore, the results demonstrate that ISS prepriming can induce immune responses that are significantly stronger than with ISS/antigen covaccination. ISS prepriming offers an :alternative approach to the traditional use of adjuvants (i.e., antigen/adjuvant coinje ction) and expands the potential clinical applications for ISS. (C) 1999 Ac ademic Press.