In-vitro diagnostics of Hymenoptera venom allergy

In-vitro diagnostics of Hymenoptera venom allergy Patients with a history of anaphylactic sting reactions require an allergological work-up (history, in-vitro tests, and skin tests) to clarify indications on venom immunotherapy and on the type of venom to be used. To demonstrate a venom sensitisation, measurement of IgE-antibodies (sIgE) specific to the natural composite venom is the standard in-vitro method. In-vitro tests are performed after a field sting reaction. After a sting, an increase of sIgE concentrations, which is followed by a decrease, indicates a previous exposure, and may help to identify the culprit venom. If the eliciting insect is doubtful, it is recommended to do repeated measurements shortly after a sting. In adults measurement of baseline serum tryptase concentration should be included into routine diagnostics of venom allergy. If a sensitisation to the presumably causative composite venom cannot be demonstrated, one may determine sIgE to recombinant COD-free allergen compounds, thereby possibly demonstrating a sensitisation to molecular venom allergens. In addition, one should consider the involvement of in Germany rare elicitors of insect sting anaphylaxis, such as bumble bees, hornets, Dolichovespula, or Polistes. If these rare elicitors could have been involved into allergic reactions, one should test patients for IgE specific to the respective venom. Moreover, several cellular tests (e.g., basophil activation test) are available to confirm venom sensitisation. Herein basophils, which carry cell-bound sIgE, can be used to confirm the involvement of suspected venoms (e.g., by showing a histamine release or up-regulation of cell surface markers upon incubation with venom allergens). Double sensitisation to both honey bee and vespid venom may either indicate true double sensitisation or cross sensitisation. In double-sensitized patients, inhibition tests and tests using molecular allergens may help to clarify the diagnosis. Results of the above mentioned in-vitro tests, however, do not precisely correlate with the clinical relevance of the putative elicitor. Double sensitisation to both honey bee and vespid venom may either indicate true double sensitisation or cross sensitisation. In double-sensitized patients inhibition tests, and tests with molecular allergens may help to specify the diagnosis. None of the mentioned in-vitro tests, however, allows a precise prognosis with respect to clinical relevance