Liposomes as carriers for allergy immunotherapy


Carmen Audera, Alergia e Inmunologia Abello S.A., e/Miguel Fleta 19, 28037 Madrid. Spain.


With the aim of obtaining an efficient but safer vaccine for allergy immunotherapy, the possibility of using liposomes as adjuvants has been considered given their proven low toxicity, adjuvant properties and ability to maintain the encapsulated substance in their interior for sonic time in vivo. Different methods of encapsulating allergenic extracts into neutral, positively, and negatively charged DPPC: cholesterol liposomes have been investigated and the immune response provoked by these in mice was studied and compared to the immune response to free allergen or other adjuvants such as aluminium hydroxide. The results obtained show that allergen encapsulated in all three types of liposomes elicit an increase in specific IgG levels higher than that provoked by free allergen, however, both encapsulation efficiency and specific FgG litre were higher when positively charged (DPPC.-cholesterol steurylamine) liposomes were used. Specific IgF. levels to allergen in positive and neutral liposomes was lower than to allergen in negative liposomes or adsorbed to A1(OH)3 No differences were found in the behaviour of liposomes prepared by different methods (the results were obtained from pooled sera from different groups of mice so there is no statistical data). These results confirm the immunoadjuvanl effect of liposomes for allergy immunotherapy. Further studies to determine their lack of toxicity, pharmacokinetic studies and human clinical studies are necessary to confirm their adequacy for human use and advantage over current immunotherapy methods.