Allergy最新文献

Background: In Type I hypersensitivity, IgE is the antibody that contributes to the onset of anaphylaxis through the activation of effector cells, causing the release of allergic mediators. Blocking IgE activity with anti-IgE autoantibodies induced by active immunization could potentially offer an efficient and cost-effective method to treat allergic disorders. We recently developed an effective and safe anti-IgE vaccine in mice, but the mechanisms by which the vaccine protects and the explanation for its safety remained largely unknown. Here, our objective was to better understand those mechanisms.

Methods: CuMV_TT-Cε3-Cε4 is a virus-like particles (VLP)-based vaccine designed to target domains 3 and 4 of IgE. Here, we studied the role of FcγRIIb and CD23 in vaccine-mediated protection from allergy using FcγRIIb KO and CD23 KO mice. Moreover, vaccine-induced IgGs were purified for passive immunization studies and for in vitro experiments with murine bone marrow-derived mast cells (BMMCs).

Results: Immunized mice generated high titers of IgG antibodies specific for IgE that conferred protection against allergic responses, independently of FcγRIIb and CD23. Sera of immunized mice blocked IgE binding to BMMC FcεRI and suppressed degranulation, independent of FcγRIIb. Purified anti-IgE antibodies did not provoke an anaphylactic response when transferred into allergic mice but protected against subsequent allergen challenge. Interestingly, the purified IgG antibodies were unable to recognize receptor-bound IgE in BMMCs, explained by the finding that recognition by these anti-IgEs depends on the same mannose moieties on IgE that are essential for FcεRI binding and thus hidden when receptor-bound.

Conclusions: In conclusion, the CuMV_TT-Cε3-Cε4 vaccine induces high titers of anti-IgE IgGs that confer protection by neutralizing IgE through its glycan epitopes, without causing FcεRI cross-linking. Our results imply that an anti-IgE vaccine may represent a promising therapeutic strategy, offering effective protection while minimizing the risk of adverse reactions similar to the monoclonal antibody omalizumab.

Immediate drug hypersensitivity reactions (IDHRs) pose significant diagnostic challenges, often requiring potentially hazardous drug challenge testing (DCT). Flow cytometry-based cellular tests including the basophil activation test (BAT), the mast cell activation test (MAT) and the T cell activation test (TAT) offer promising alternatives to reduce DCT reliance. While these tests are still in development, they demonstrate potential to compete with skin tests by providing superior diagnostic performance and improved patient safety by reducing the need for DCT. Furthermore, it is encouraging that these flow cytometry-based tests are also suitable for challenging populations, such as children. Despite requiring specialised infrastructure, these tests have the potential to be cost-effective when performed in reference centres and may offer unique mechanistic insights into immediate drug hypersensitivity reactions. However, further research is needed to validate their reliability, address pharmaceutical-specific testing considerations, and potentially integrate them into clinical guidelines.

Background: Molecular forms of allergen-specific immunotherapy (AIT) for cat allergy are needed. Fel d 1, Fel d 4, and Fel d 7 are the most important cat allergens.

Methods: IgE epitopes of Fel d 4 and Fel d 7 were mapped by blocking allergic patients' IgE binding with allergen peptide-specific antisera. Five recombinant fusion proteins (PreS-Cat 1-PreS-Cat 5) each containing hepatitis B virus (HBV)-derived PreS as an immunological carrier and non-allergenic peptides from the IgE binding sites of Fel d 1, Fel d 4, and Fel d 7 were expressed in Escherichia coli, purified, and characterized by mass spectrometry, circular dichroism (CD), and size exclusion chromatography. ImmunoCAP and basophil activation experiments demonstrated the hypoallergenic activity of PreS-Cat 1-5. The ability of PreS-Cat 1-5 to induce IgE-blocking antibodies in rabbits was compared to three licensed allergen extract-based AIT vaccines. PreS-Cat 1-5-specific IgG antibodies were tested for inhibition of allergen-specific IgE binding and specific basophil activation. T cell activation and induction of specific cytokine secretion by PreS-Cat proteins were compared with cat allergens in PBMC cultures.

Results: Recombinant hypoallergenic, biochemically and structurally defined PreS-Cat 1-5 were obtained. Two subcutaneous immunizations of rabbits with PreS-Cat 1-5 induced equal (Fel d 1) or better (Fel d 4 and Fel d 7) antibodies (PreS-Cat 5 > PreS-Cat 1 > PreS-Cat 3) blocking allergic patients' IgE binding to cat allergens than six to fifteen immunizations with allergen extract-based vaccines. PreS-Cat-specific antibodies strongly inhibited specific basophil activation. PreS-Cat 5 > PreS-Cat 1 induced significantly more IL-10 in cultured PBMCs from cat allergic patients than cat allergens.

Conclusions: PreS-Cat 5 and PreS-Cat 1 are highly promising molecular vaccine candidates for AIT of cat allergy, combining Fel d 1-, Fel d 4-, and Fel d 7-peptides in single PreS fusion proteins.