Allergens entrapped in liposomes reduce allergenicity and induce immunogenicity on repeated injections in mice.

Liposomes which are nontoxic, biodegradable and biocompatible lipid vesicles are known to act as adjuvants and can be used to formulate sustained release preparation by encapsulation. In the present study, allergen entrapped in liposomes were injected at different time intervals in Swiss mice (made responders to IgE by injecting cyclophosphamide) and Balb/C mice (high IgE responders). Tissue distribution studies after intraperitoneal injection of allergen (entrapped and untrapped) revealed that liposome-entrapped allergen was retained for a longer time in all the tissues except kidney as compared to the free allergen given similarly. It was observed that serum specific IgG antibody levels were higher and specific IgE levels were lower in animals given repeated injections of liposomes-entrapped allergen as compared to those animals injected free allergen in the same manner. The entrapment of allergen in liposomes somehow suppressed the specific IgE response on repeated injections. The immunomodulatory effect of liposomes may be useful in the immunotherapy of respiratory allergic disorders.