The present invention provides particles comprising chitosan, or a derivativethereof, useful as delivery vehicles for polynucleotides encodingpolypeptides, compositions comprising such particles and a pharmaceuticallyacceptable carrier, and methods for delivering polynucleotides using suchparticles. Optionally, the particles of the invention further comprise a lipidcomponent. The present further provides a method for enhancing interferon-gamma expression to regulate the production of cytokines secreted by T-helpertype 2 (Th2) cells within a subject by administering an effective amount of aparticle of the subject invention to the subject, wherein the particlecomprises a polynucleotide encoding interferon-gamma.
