Value of component based diagnostics in IgE-mediated hymenoptera sting reactions

[Basophil activation test to follow-up of patients treated with hymenoptera venom immunotherapy: a review of current evidence]

Hymenoptera venom immunotherapy (HVI) is a long-term effective treatment to avoid new systemic reactions in patients with Hymenoptera allergy. The sting challenge test is considered the gold standard to confirm the tolerance. However, the use of this technique is not generalized in clinical practice, being the basophil activation test (BAT), which functionally explores allergen response, an alternative that does not entail any of the provocation risks associated with the sting challenge test. This study reviews the publications that used the BAT to follow up and evaluate the success of the HVI. Studies assessing the changes between a baseline BAT before the start and BATs performed between the starting and maintenance phases of the HVI were selected. Ten articles were found, comprising information from 167 patients, of which 29% used the sting challenge test. The studies concluded the importance of evaluating the responses with submaximal allergen concentrations, which reflect basophil sensitivity, to monitor the HVI using the BAT. It was also observed that changes in the maximum response (reactivity) could not reflect the clinical status of tolerance, particularly in the initial phases of HVI.

Component-resolved diagnosis in vespid venom-allergic individuals

BACKGROUND

Hymenoptera venom-allergic patients frequently present multiple sensitisations.

OBJECTIVES

To define the allergic profile by components in wasp allergic patients. To study the usefulness of specific IgE to components in cases of double sensitisation.

MATERIALS AND METHODS

Wasp allergic patients who needed Polistes and/or Vespula venom immunotherapy were included. Before immunotherapy and after two years of treatment the following specific IgE (sIgE) levels were measured: Apis mellifera, Vespula spp. Polistes spp., rVes v 5, rPol d 5, nVes v 5, nPol d 5, nVes v 1, nPol d 1, nApi m 1, nApi m 2 and peroxidase. Skin tests with venoms were performed. Based on the sIgE and the skin test results, Polistes and/or Vespula immunotherapy was administered.

RESULTS

Thirteen patients were included. Double sensitisation to Polistes/Vespula was detected in eight patients. Sensitisation to rVes v 5 and rPol d 5 was found in two of eight cases, to nVes v 1 and nPol d 1 in eight of 13 cases, and to nVes v 5 and nPol d 5 in 2 of 13 cases. Three patients received double immunotherapy with both wasps. One patient was treated with Vespula and nine with Polistes. sIgE levels decreased after two years of treatment. In patients who showed double sensitisation but were treated with only one venom, sIgE to both venoms decreased.

CONCLUSIONS

Components analysis can be useful to study double positivity. In case of doubt, double immunotherapy should be administered. Phospholipase was found to be a major allergen in our population.

In vitro diagnosis of Hymenoptera venom allergy and further development of component resolved diagnostics

For most people Hymenoptera stings result in transient and bothersome local inflammatory responses characterized by pain, itching, redness and swelling. In contrast, for those presenting an IgE-mediated allergic reaction, a re-sting may cause life-threatening reactions. In such patients, correct diagnosis is an absolute prerequisite for effective management, i.e. venom-specific immunotherapy. Generally, identification of the offending insect involves a detailed history along with quantification of venom-specific IgE antibodies and venom skin tests. Unfortunately, due to uncertainties associated with both tests, correct diagnosis is not always straightforward. This review summarizes the potentials and limitations of the various in vitro tests that are currently being used in the diagnosis of Hymenoptera venom allergy. Particular attention is paid to the potential of novel cellular tests such as basophil activation tests and component-resolved diagnosis with recombinant venom allergens in the diagnostic approach of patients with difficult diagnosis, i.e. cases in whom traditional venom specific IgE and skin tests yield equivocal or negative results. Finally, this review also covers the recent discoveries in the field of proteome research of Hymenoptera venoms and the selection of cell types for recombinant allergens production.

Component-resolved diagnosis of wasp (yellow jacket) venom allergy

BACKGROUND

Wasp venom allergy is a potentially life-threatening condition with serious consequences of diagnostic error.

OBJECTIVE

To assess whether component-resolved diagnosis, using non-glycosylated recombinant allergen components from yellow jacket can add to the diagnosis of wasp venom allergy.

METHODS

In total, 148 patients with a wasp (yellow jacket) allergy were included, 91 with unequivocal tests, 26 with double positivity of serum-specific IgE (sIgE) to both venoms, 21 with discrepant sIgE and skin test results and finally 10 having their diagnosis only confirmed by basophil activation test (negative sIgE and skin test results). Specific IgE to recombinant species-specific allergen components Ves v 1 and Ves v 5 from yellow jacket, Api m 1 from honeybee and Ves v 5 complemented wasp venom were tested by ImmunoCAP.

RESULTS

Overall, combined use of sIgE to rVes v 1 and rVes v 5 allowed correct diagnosis in 139 of the 148 patients (94%) and rApi m 1 was demonstrable in only one patient. Supplementing the traditional yellow jacket allergosorbent with rVes v 5 allowed to correctly diagnose wasp allergy in patients sensitized to Ves v 5 but demonstrating a negative sIgE to wasp venom.

CONCLUSION

Component-resolved diagnoses with the wasp-specific recombinant allergen components Ves v 1 and Ves v 5 is a reliable method to diagnose yellow jacket allergy and can help to take out the sting of difficult cases. However, as the number of patients with doubt after conventional tests is small, larger collaborative studies are needed to draw more definitive conclusions. Whether the rVes v 5 supplemented yellow jacket allergosorbent constitutes an asset in the diagnostic management of wasp venom allergy remains to be further established.

Overview of component resolved diagnostics

Component-resolved diagnostics (CRD) utilize purified native or recombinant allergens to detect IgE sensitivity to individual allergen molecules and have become of growing importance in clinical investigation of IgE-mediated allergies. This overview updates current developments of CRD, including multiarray test systems. Cross-reactions between allergens of known allergen families (i.e. to Bet v 1 homologues) are emphasised. In pollinosis as well as in allergy to hymenoptera venoms or to food, CRD allows to some extent discrimination between clinically significant and irrelevant sIgE results and the establishing of sensitisation patterns with particular prognostic outcomes (i.e. sensitisations to storage proteins which correlate with clinically severe reactions in peanut allergy). Further promising improvements in diagnostics are expected from additional, not yet commercially available, recombinant allergen diagnostics identifying particular molecules of risk. Overall, CRD may decrease the need for provocation testing and may also improve the specificity of allergen-specific immunotherapy.