Immunization via hair follicles by topical application of naked DNA to normal skin

In order to test the immune response generated to small amounts of foreign protein in skin, we applied naked DNA in aqueous solution to untreated normal skin. Topical application of plasmid expression vectors for lacZ and the hepatitis B surface antigen (HBsAg) to intact skin induced antigen-specific immune responses that displayed T-H2 features. For HBsAg, specific antibody and cellular responses were induced to the same order of magnitude as those produced by intramuscular injection of the commercially available recombinant HBsAS polypeptide vaccine. Finally, topical gene transfer was dependent on the presence of normal hair follicles.