Modulation of the Humoral Response to Dermatophagoides pteronyssinus Allergens in BALB/c Mice by Extract Modification and Adjuvant Use

Abstract

Background: Currently, several strategies are being used in order to improve the safety and efficacy of allergen-specific immunotherapy; these strategies include the use of modified hypoallergenic extracts as well as different adjuvants with immunomodulatory properties in combination with native or modified extracts. The objectives of this study were to investigate the humoral response generated in mice to modified Dermatophagoides pteronyssinus extracts in the presence or absence of two different adjuvants. Methods: BALB/c mice were inoculated either with native, depigmented or depigmented-polymerised D. pteronyssinus without adjuvants or combined with aluminium hydroxide or oligodeoxinucleotides containing CpG motifs. IgE concentration, specific total IgG, IgG1 and IgG2a titres were measured in mice sera and cross-reactivity inhibition experiments were performed. IgG antigenic profiles were obtained by immunoblotting for all formulations. Results: Inoculation of depigmented-polymerised extract induced statistically significant lower IgE levels than the native extract even when adsorbed onto aluminium hydroxide. When this extract was inoculated in the presence of oligodeoxinucleotides containing CpG motifs, it elicited high IgG levels, a high IgG2a/lgG1 ratio and low IgE production. Furthermore, the antigenic profiles observed after extract inoculation showed punctual differences between the depigmented-polymerised extract and the native or depigmented extracts. Conclusions: Our results suggest that the depigmentation and polymerisation process modifies the native extract’s antigenic and immunogenic properties and converts the depigmented-polymerised extract into a better choice for allergen-specific immunotherapy.