Immunological consequences of nasal drug delivery in dextran microspheres and ethyl(hydroxyethyl)cellulose in rats

These experiments were performed to evaluate the immunological implications of intranasal drug delivery in dextran microspheres and a thermogelling ethyl(hydroxyethyl)cellulose (EHEC) system. The amount of IgA and IgG in plasma and nasal washings from rats administered with equine myoglobin in the two nasal delivery systems were not significantly different from the controls throughout the experiment. The intranasal administration generated neither specific IgA nor IgG antibodies in plasma or in nasal washings. When the animals were boosted intramuscularly with Freund's complete adjuvant on day 26 they produced a plasma IgG response similar to the response in animals that received one intramuscular injection of equine myoglobin in Freund's complete adjuvant on day 1. The conclusion is therefore that dextran microspheres and EHEC do not act as adjuvants, potentiating the immunogenicity of heterogeneous proteins. This is an important property for a nasal drug delivery system to fulfil.