T cell epitopes of the timothy grass pollen allergen Phl p 5 of mice and men and the detection of allergen-specific T cells using Class II Ultimers.

BACKGROUND: Knowledge of allergen-specific T cell epitopes is a prerequisite not only for therapeutic approaches but also for elucidating immunological mechanisms of type I allergy. Ex vivo detection of allergen-specific T cells using class II tetramer technology has become an important tool for investigating immune responses in atopic and healthy individuals. METHODS: Using (3)H-thymidine incorporation assays, T cell epitopes specific for the major timothy grass pollen allergen Phl p 5.0101 were mapped in 11 allergic donors and two different mouse strains. Different protocols for expansion/restimulation of T cells from the blood of allergic donors and detection of allergen-specific T cells by Class II Ultimer staining were evaluated. RESULTS: We identified several new Phl p 5.0101 class II T cell epitopes in allergic patients and confirmed previously published ones. Additionally, we discovered the major T cell epitopes in BALB/c and C57BL/6 mice. Using a novel Class II Ultimer, we detected epitope-specific T cells expanded from the blood of an allergic donor. CONCLUSIONS: Epitope mapping of Phl p 5.0101 revealed an immunodominant epitope in BALB/c and C57BL/6 mice and an immunodominant region in humans (amino acids 259-282), which was recognized by 8 out of 11 allergic donors. Detection of Phl p 5-specific T cells was demonstrated using a Class II Ultimer specific for epitope 196-210. Successful detection of ultimer-positive T cells was strongly dependent on a resting phase after in vitro expansion.

Immunize and disappear-safety-optimized mRNA vaccination with a panel of 29 allergens.

BACKGROUND: The spread of type I allergic diseases has reached epidemic dimensions. The success of therapeutic intervention is limited, and hence prophylactic vaccination is now seriously considered. However, immunization of healthy individuals requires safety standards far beyond those applicable for therapeutic approaches. mRNAs encoding allergen molecules represent an attractive tool for preventive vaccination because of the inherent safety features of this vaccine type. OBJECTIVE: In the current study we investigated whether mRNA constructs would be capable of protecting against type I allergic reactions in a murine model using the grass pollen allergen Phl p 5 and 28 other major pollen, food, animal, mold, and latex allergens. METHODS: BALB/c mice were immunized intradermally either with conventional or replicase-based mRNA constructs. Subsequently, animals were sensitized by means of subcutaneous injection of allergen/alum, followed by airway provocation. IgG1/IgG2a/IgE titers were determined by using ELISAs. Allergen-specific functional IgE levels were assessed by using the basophil release assay. Measurement of cytokines in splenocyte cultures and bronchoalveolar lavage fluids were performed by using enzyme-linked immunosorbent spot assays/sandwich ELISAs. Eosinophil and CD8(+) counts in bronchoalveolar lavage specimens were determined by means of flow cytometry. Airway hyperreactivity was assessed with whole-body plethysmography and invasive resistance/dynamic compliance measurement. RESULTS: mRNA vaccination proved its antiallergic efficacy in terms of IgG subclass distribution, functional IgE suppression, reduction of IL-4 and IL-5 levels, induction of IFN-gamma-producing cells, and reduction of airway hyperreactivity and eosinophil counts in the lung. CONCLUSION: Immunization with mRNA induces T(H)1-biased immune responses similar to those elicited through DNA-based vaccination but additionally offers the advantage of a superior safety profile.

mRNA vaccination as a safe approach for specific protection from type I allergy.

Allergic diseases are on the increase and current therapies are lacking in efficacy and patient compliance. In recent years, the idea of prophylactic measures, especially for children at high risk for allergy, has become increasingly popular. This review summarizes the available preclinical data for protective allergy vaccines, with a focus on one of the most promising vaccine candidates; mRNA vaccines. Recently, mRNA vaccines have been rediscovered as an alternative to their more prominent counterparts, the DNA vaccines. Allergen-encoding mRNA vaccines elicit long-lasting protection from sensitization, and induce a type of immunity similar to the natural protective response that is acquired in the presence of microbial burden early in life. Owing to their excellent safety profile, they represent the ideal candidates for a vaccine that aims to protect at-risk children who have not yet been sensitized to allergens.

Prophylactic mRNA vaccination against allergy.

PURPOSE OF REVIEW: mRNA vaccines have recently been re-discovered as an attractive alternative to the more prominent DNA vaccines, as they harbor many advantages with respect to safety and regulatory issues. Whereas most mRNA vaccines are focused on tumor therapy, this type of vaccine has now also been successfully employed for prophylactic immunization against type I allergy in a mouse model. This concept differs from conventional immunotherapy in that it relies on immune deviation toward a TH1 phenotype, rather than induction of regulatory T cells or tolerance. RECENT FINDINGS: Conventional as well as self-replicating mRNA vaccines have demonstrated their potential to prevent the induction of an allergic phenotype in terms of allergen-specific IgE, allergy-associated cytokine profiles, eosinophilic lung infiltration, and airway hyperreactivity. Preliminary data raise the question whether TH1 immune deviation induced by mRNA vaccination resembles the natural phenotype of a certain proportion of nonatopic individuals.Reservations regarding Good Manufacturing Practices manufacture costs, shelf life stability, and lack of immunogenicity due to rapid in-vivo degradation have been overcome by novel findings. SUMMARY: mRNA vaccines open the field for a safety-optimized prophylactic vaccination against allergic diseases. Future studies concerning long-term effects and vaccine-induced versus natural immune responses will be needed to transfer this knowledge to the clinics.