Treatment with American Polistes venom was ineffective in an Italian patient allergic to European Polistes

Allergen Content of Therapeutic Preparations for Allergen-Specific Immunotherapy of European Paper Wasp Venom Allergy

Allergy to Polistes dominula (European paper wasp) venom is of particular relevance in Southern Europe, potentially becoming a threat in other regions in the near future, and can be effectively cured by venom immunotherapy (VIT). As allergen content in extracts may vary and have an impact on diagnostic and therapeutic approaches, the aim was to compare five therapeutic preparations for VIT of P. dominula venom allergy available in Spain. Products from five different suppliers were analyzed by SDS-PAGE and LC-MS/MS and compared with a reference venom sample. Three products with P. dominula venom and one product with a venom mixture of American Polistes species showed a comparable band pattern in SDS-PAGE as the reference sample and the bands of the major allergens phospholipase A1 and antigen 5 were assignable. The other product, which consists of a mixture of American Polistes species, exhibited the typical band pattern in one, but not in another sample from a second batch. All annotated P. dominula allergens were detected at comparable levels in LC-MS/MS analysis of products containing P. dominula venom. Due to a lack of genomic information on the American Polistes species, the remaining products were not analyzed by this method. The major Polistes allergens were present in comparable amounts in the majority, but not in all investigated samples of venom preparations for VIT of P. dominula venom allergy.

Management of Double Sensitization to Vespids in Europe

Wasp allergy with a diagnostic profile of double sensitizations to vespid venom is a frequent clinical problem in areas where different genera of wasps are present. Identification of the insect responsible for serious reactions poses a diagnostic challenge as the only effective treatment to date is immunotherapy based on the specific venom. In southern Europe, the double sensitization to Vespula and Polistes venoms is highly frequent. It has been shown that the major allergenic proteins (Phospholipase A1 and Antigen 5) share sequences across the different genera and species, which would be the cause of cross-reactivity. Additionally, the minor allergens (Dipeptidyl-peptidases, Vitellogenins) have been found to share partial sequence identity. Furthermore, venom contains other homologous proteins whose allergenic nature still remains to be clarified. The traditional diagnostic tools available are insufficient to discriminate between allergy to Vespula and Polistes in a high number of cases. IgE inhibition is the technique that best identifies the cross-reactivity. When a double sensitization has indeed been shown to exist or great uncertainty surrounds the primary sensitization, therapy with two venoms is advisable to guarantee the safety of the patient. In this case, a strategy involving alternate administration that combines effectiveness with efficiency is possible.

Hymenoptera Allergy and Mast Cell Activation Syndromes

Mast cell activation syndrome (MCAS) can be diagnosed in patients with recurrent, severe symptoms from mast cell (MC)-derived mediators, which are transiently increased in serum and are attenuated by mediator-targeting drugs. When KIT-mutated, clonal MC are detected in these patients, a diagnosis of primary MCAS can be made. Severe systemic reactions to hymenoptera venom (HV) represent the most common form of anaphylaxis in patients with mastocytosis. Patients with primary MCAS and HV anaphylaxis are predominantly males and do not have skin lesions in the majority of cases, and anaphylaxis is characterized by hypotension and syncope in the absence of urticaria and angioedema. A normal value of tryptase (≤11.4 ng/ml) in these patients does not exclude a diagnosis of mastocytosis. Patients with primary MCAS and HV anaphylaxis have to undergo lifelong venom immunotherapy, in order to prevent further potentially fatal severe reactions.

Component-resolved diagnosis of vespid venom-allergic individuals: phospholipases and antigen 5s are necessary to identify Vespula or Polistes sensitization

BACKGROUND

Cross-reactivity between hymenoptera species varies according to the different allergenic components of the venom. The true source of sensitization must therefore be established to ensure the efficacy of venom immunotherapy.

OBJECTIVE

In the Mediterranean region, Polistes dominulus and Vespula spp. are clinically relevant cohabitating wasps. A panel of major vespid venom allergens was used to investigate whether serum-specific IgE (sIgE) could be used to distinguish sensitization to either vespid.

METHODS

Fifty-nine individuals with allergic reactions to vespid stings and positive ImmunoCAP and/or intradermal tests to vespid venoms were studied. sIgE against recombinant and natural venom components from each wasp species was determined using the ADVIA Centaur(®) system.

RESULTS

sIgE against recombinant antigen 5s sensitization to be detected in 52% of the patients tested (13/25). The sensitivity increased to 80% (20/25), when using natural antigen 5s, and to 100% with the complete panel of purified natural components, because the sIgE was positive to either the antigen 5s (Pol d 5/Ves v 5) or to the phospholipases (Pol d 1/Ves v 1) of the two vespids, or to both components at the same time. In 69% of cases, it was possible to define the most probable sensitizing insect, and in the rest, possible double sensitization could not be excluded. Vespula hyaluronidase was shown to have no additional value as regards the specificity of the assay.

CONCLUSIONS

The major allergens of P. dominulus' and Vespula vulgaris' venom, namely phoshpholipases and antigen 5s, are required to discriminate the probable sensitizing species in vespid-allergic patients.

Structural biology of allergens from stinging and biting insects

PURPOSE OF REVIEW

Modern techniques in genomic and protein research are applied to the study of stinging and biting insect allergens.

RECENT FINDINGS

Three-dimensional structures of additional insect venom and salivary allergens have been determined. An approach to determining B-cell epitopes has been used for hyaluronidase. A number of new venom and salivary allergens have been characterized. The structures and significance of several insect allergens have been updated. Investigations continue into distinguishing venom crossreactivity from multiple sensitization. Further studies are clarifying the significance of carbohydrate epitopes. Genomic and proteomic techniques are being used in the investigation of proteins and peptides in insect venom and saliva.

SUMMARY

The nature of venom crossreactivity and the B-cell and T-cell epitope structures of insect venom and salivary allergens are beginning to be elucidated.