RESUMEN
BACKGROUND: Allergen products for subcutaneous immunotherapy (SCIT) contain intact allergen extracts or chemically modified allergoids. Chemical modification was introduced to reduce allergenicity while retaining immunogenicity and thereby enable safer and more efficient allergy immunotherapy. METHODS: Experimental allergoids were produced from intact allergen extract for birch, grass, and house dust mite (HDM) to evaluate the effects of chemical modification. Preparations were compared with commercial allergoids and analyzed using SDS-PAGE/immunoblotting, IgE-inhibition assays, and crossed immunoelectrophoresis (CIE). Dermatophagoides pteronyssinus (Der p) vaccines were also tested for protease activity and immunizing capacity in a mouse model. RESULTS: The composition of IgE-binding epitopes in allergoids differed from that of intact allergen vaccines. Birch and grass allergoids produced smears of protein aggregates on SDS-PAGE, whereas intact allergen preparations showed distinct protein bands as expected. Der p allergoid vaccines, however, showed a distinct protein band corresponding to major allergen Der p 1 in both SDS-PAGE and CIE analysis, and commercial Der p allergoid vaccines showed Der p 1-related cysteine protease activity. CONCLUSION: Allergoids and intact allergen preparations differ with respect to the composition of IgE-binding epitopes. However, chemical cross-linking does not affect every allergen molecule to the same degree. Der p 1, for example, remains largely unmodified. Furthermore, the investigational HDM allergoid vaccines showed reduced and delayed immune responses when used for immunization of mice.
Asunto(s)
Hipersensibilidad , Vacunas , Ratones , Humanos , Animales , Alérgenos , Alergoides , Hipersensibilidad/terapia , Inmunoterapia , Pyroglyphidae , Poaceae , Epítopos , Inmunoglobulina E , Extractos Vegetales , Antígenos DermatofagoidesRESUMEN
Background: Allergen products for subcutaneous immunotherapy (SCIT) contain intact allergen extracts or chemically modified allergoids. Chemical modification was introduced to reduce allergenicity while retaining immunogenicity and thereby enable safer and more efficient allergy immunotherapy. Methods: Experimental allergoids were produced from intact allergen extract for birch, grass, and house dust mite (HDM) to evaluate the effects of chemical modification. Preparations were compared with commercial allergoids and analyzed using SDS-PAGE/immunoblotting, IgE-inhibition assays, and crossed immunoelectrophoresis (CIE). Dermatophagoides pteronyssinus (Der p) vaccines were also tested for protease activity and immunizing capacity in a mouse model. Results: The composition of IgE-binding epitopes in allergoids differed from that of intact allergen vaccines. Birch and grass allergoids produced smears of protein aggregates on SDS-PAGE, whereas intact allergen preparations showed distinct protein bands as expected. Der p allergoid vaccines, however, showed a distinct protein band corresponding to major allergen Der p 1 in both SDS-PAGE and CIE analysis, and commercial Der p allergoid vaccines showed Der p 1related cysteine protease activity. Conclusion: Allergoids and intact allergen preparations differ with respect to the composition of IgE-binding epitopes. However, chemical cross-linking does not affect every allergen molecule to the same degree. Der p 1, for example, remains largely unmodified. Furthermore, the investigational HDM allergoid vaccines showed reduced and delayed immune responses when used for immunization of mice (AU)
Antecedentes: Los productos de alérgenos para inmunoterapia subcutánea (SCIT) contienen extractos de alérgenos intactos o alergoides modificados químicamente. En este trabajo se ha hecho una modificación química para reducir la alergenicidad a la vez que se conservaba la inmunogenicidad, y por lo tanto, permitir una inmunoterapia más segura y eficiente. Métodos: Se produjeron alergoides experimentales a partir de extracto de alérgeno intacto para abedul, hierba y ácaros del polvo doméstico (HDM) y se evaluaron los efectos de la modificación química realizada. Las preparaciones se compararon con alergoides comerciales y se analizaron mediante SDS-PAGE/inmunotransferencia, ensayos de inhibición de IgE e inmunoelectroforesis cruzada (CIE). Las vacunas de Dermatophagoides pteronyssinus (Der p) también se probaron para determinar la actividad de la proteasa y la capacidad de inmunización en un modelo de ratón. Resultados: La composición de los epítopos de unión a IgE en los alergoides difería de las vacunas de alérgenos intactas. Los alergoides de hierba y abedul produjeron manchas de agregados de proteínas en el SDS-PAGE, mientras que las preparaciones de alérgenos intactos mostraron distintas bandas de proteínas como se esperaba. Las vacunas alergoides Der p, sin embargo, mostraron una banda de proteína distinta de la correspondiente al alérgeno principal Der p 1 en los análisis SDS-PAGE y CIE. Las vacunas alergoides comerciales Der p mostraron actividad de cisteína proteasa relacionada con Der p 1.Conclusión: Los alergoides y las preparaciones de alérgenos intactos difieren con respecto a la composición de los epítopos de unión a IgE; sin embargo, el entrecruzamiento químico no afecta a todas las moléculas de alérgenos de un modo similar. Der p 1, por ejemplo, permanece prácticamente sin modificar. Además, las vacunas alergoides de HDM produjeron respuestas inmunitarias reducidas y tardías cuando se usaron para la inmunización de ratones (AU)
Asunto(s)
Animales , Ratones , Alérgenos/clasificación , Antígenos Dermatofagoides/inmunología , Hipersensibilidad/etiología , Hipersensibilidad/terapia , Desensibilización Inmunológica , Vacunas , Modelos Animales de Enfermedad , Epítopos , Inmunoglobulina E/inmunología , Poaceae , PyroglyphidaeRESUMEN
Allergen-specific immunotherapy (SIT) is a clinically effective therapy for immunoglobulin (Ig)E-mediated allergic diseases. To reduce the risk of IgE-mediated side effects, chemically modified allergoids have been introduced. Furthermore, adsorbance of allergens to aluminium hydroxide (alum) is widely used to enhance the immune response. The mechanisms behind the adjuvant effect of alum are still not completely understood. In the present study we analysed the effects of alum-adsorbed allergens and allergoids on their immunogenicity in vitro and in vivo and their ability to activate basophils of allergic donors. Human monocyte derived dendritic cells (DC) were incubated with native Phleum pratense or Betula verrucosa allergen extract or formaldehyde- or glutaraldehyde-modified allergoids, adsorbed or unadsorbed to alum. After maturation, DC were co-cultivated with autologous CD4(+) T cells. Allergenicity was tested by leukotriene and histamine release of human basophils. Finally, in-vivo immunogenicity was analysed by IgG production of immunized mice. T cell proliferation as well as interleukin (IL)-4, IL-13, IL-10 and interferon (IFN)-γ production were strongly decreased using glutaraldehyde-modified allergoids, but did not differ between alum-adsorbed allergens or allergoids and the corresponding unadsorbed preparations. Glutaraldehyde modification also led to a decreased leukotriene and histamine release compared to native allergens, being further decreased by adsorption to alum. In vivo, immunogenicity was reduced for allergoids which could be partly restored by adsorption to alum. Our results suggest that adsorption of native allergens or modified allergoids to alum had no consistent adjuvant effect but led to a reduced allergenicity in vitro, while we observed an adjuvant effect regarding IgG production in vivo.
Asunto(s)
Adyuvantes Inmunológicos , Alérgenos/inmunología , Hidróxido de Aluminio/inmunología , Extractos Vegetales/inmunología , Alérgenos/química , Alergoides , Compuestos de Alumbre/toxicidad , Hidróxido de Aluminio/química , Animales , Apoptosis/genética , Apoptosis/inmunología , Basófilos/inmunología , Basófilos/metabolismo , Citocinas/biosíntesis , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Femenino , Liberación de Histamina/inmunología , Humanos , Inmunoglobulina G/inmunología , Leucotrienos/metabolismo , Activación de Linfocitos/inmunología , Ratones , Extractos Vegetales/química , Subgrupos de Linfocitos T/inmunologíaRESUMEN
Different vaccines containing intact allergens or chemically modified allergoids as active ingredients are commercially available for specific immunotherapy. Allergoids are claimed to have decreased allergenicity without loss of immunogenicity and this is stated to allow administration of high allergoid doses. We compared the allergenicity and immunogenicity of four commercially available chemically modified grass pollen allergoid products with three commercially available intact grass pollen allergen vaccines. The allergenicity was investigated with immunoglobulin (Ig)E-inhibition and basophil activation assays. Human T cell proliferation and specific IgG-titres following mouse immunizations were used to address immunogenicity. Furthermore, intact allergen vaccines with different contents of active ingredients were selected to study the influence of the allergen dose. In general, a lower allergenicity for allergen vaccines was clearly linked to a reduced immunogenicity. Compared with the vaccine with the highest amount of intact allergen, the allergoids caused reduced basophil activation as well as diminished immunogenicity demonstrated by reduced T cell activation and/or reduced induction of murine grass-specific IgG antibodies. Interestingly, intact allergen vaccines with lower content of active ingredient exhibited similarly reduced allergenicity, while immunogenicity was still higher or equal to that of allergoids. The low allergenicity observed for some allergoids was inherently linked to a significantly lower immunogenic response questioning the rationale behind the chemical modification into allergoids. In addition, the linkage between allergenicity, immunogenicity and dose found for intact allergen vaccines and the immunogen as well as allergenic immune responses observed for allergoids suggest that the modified allergen vaccines do not contain high doses of immunologically active ingredients.
Asunto(s)
Alérgenos/inmunología , Poaceae/inmunología , Polen/inmunología , Vacunas/inmunología , Alérgenos/efectos de los fármacos , Alergoides , Animales , Basófilos/inmunología , Relación Dosis-Respuesta a Droga , Relación Dosis-Respuesta Inmunológica , Humanos , Inmunoglobulina E/metabolismo , Inmunoglobulina G/metabolismo , Inmunoterapia/métodos , Ratones , Ratones Endogámicos BALB C , Extractos Vegetales , Poaceae/efectos de los fármacos , Polen/efectos de los fármacos , Linfocitos T/inmunología , Vacunas/farmacologíaRESUMEN
BACKGROUND: Specific immunotherapy with intact allergen vaccine is a well-documented treatment for allergic diseases. Different vaccine formulations are currently commercially available, the active ingredient either being intact allergens or chemically modified allergoids. The rationale behind allergoids is to decrease allergenicity while maintaining immunogenicity. However, data from the German health authorities based on reporting of adverse events over a 10-year period did not indicate increased safety of allergoids over intact allergens. OBJECTIVE: The objective of this study was to investigate the effect of chemical modification on allergenicity and immunogenicity comparing four commercial allergoid products for birch pollen immunotherapy with an intact allergen vaccine. METHODS: Solid-phase IgE inhibition and histamine release assays were selected as model systems for allergenicity, and a combination of human T cell proliferation and IgG titres following mouse immunizations were used to address the immunogenicity of the intact allergen vaccine and the four allergoids. In all assays, the products were normalized with respect to the manufacturer's recommended maintenance dose. RESULTS: IgE inhibition experiments showed a change in epitope composition comparing intact allergen vaccine with allergoid. One allergoid product induced enhanced histamine release compared to the intact allergens, while the other three allergoids showed reduced release. Standard T cell stimulation assays using lines from allergic patients showed a reduced response for all allergoids compared with the intact allergen vaccine regardless of the cell type used for antigen presentation. All allergoids showed reduced capacity to induce allergen-specific IgG responses in mice. CONCLUSION: While some allergoids were associated with reduced allergenicity, a clear reduction in immunogenicity was observed for all allergoid products compared with the intact allergen vaccine, and the commercial allergoids tested therefore do not fulfil the allergoid concept.