Can serum white birch (Betula verrucosa) pollen antigen (Bet v 1) immunoglobulin E measurement distinguish between sensitization and allergy?

Component resolved analysis of ash pollen allergy in Bavaria

Background

Sensitization to ash pollen is underestimated in various regions. The prevalence in Germany is about 10%. However, allergy to ash pollen is widely overlooked by allergists, since the pollination period of ash and birch in central Europe closely overlap and rhinoconjunctival symptoms during April/May are often assigned to birch pollen. Component resolved analysis of the different ash allergens is not routinely available. Therefore, we would like to question the usefulness of component resolved diagnostic via olive components, as ash and olive are both part of the Oleaceae family.

Methods

113 patients with nasal provocation and skin prick test to ash were retrospectively compared regarding their specific immunoglobulin E antibody profiles with response to native ash extract, rOle e 1, nOle e 7 and rOle e 9.

Results

In nasal provocation testing 58% of 113 patients sensitized to ash were allergic, 42% were only sensitized without showing symptoms. Skin prick testing and serology against native ash extract detected most patients sensitized to ash pollen, whereas rOle e 1 was less sensitive. However, the value of measurements of skin prick test, serology to native ash extract and rOle e 1 did not allow a differentiation between an allergy and clinically silent sensitization. Specific antibodies to nOle e 7 and rOle e 9 were only seen in individual patients and were all positive for native ash extract and rOle e 1.

Conclusion

Skin prick testing and serology to native extract of ash pollen are the most reliable tools to diagnose a sensitization to ash pollen for patients living in Germany. Component resolved diagnostic to the major allergen rOle e 1 as representative of the Oleaceae family is possible but was less sensitive. Diagnostic of nOle e 7 and rOle e 9 did not show any additional benefit. Regarding differentiation between allergy and clinically silent sensitization to ash pollen, provocation is the leading diagnostic tool. Concluding, in routine clinical practice the standard methods-skin prick test, serology to native ash extract and provocation testing-remain crucial in the diagnosis and differentiation of ash sensitization and allergy.

The Clinical Impact of Bet v 6 in Birch Pollen-Sensitized Patients

BACKGROUND

Bet v 6, a minor birch pollen allergen, is commercially available for allergen-specific IgE antibody testing. However, there is hardly any literature on the clinical impact of Bet v 6. The aim of the present study was to analyze if testing specific IgE against Bet v 6 can add valuable benefit to the standard diagnostics of birch pollen-sensitized patients, especially in patients with unknown sensitization-eliciting allergens.

METHODS

Birch pollen-sensitized patients with missing IgE reactivity against Bet v 1, 2, and 4 were tested for specific IgE antibodies against Bet v 6. For comparison, an equal number of randomly selected patients with birch pollen sensitization, regardless of their individual sensitization patterns, were tested for specific anti-Bet v 6.

RESULTS

Of 57 cases with missing reactivity against the standard birch pollen allergens, 2 patients were positive for Bet v 6. In the representative sample, 3 patients showed specific IgE against Bet v 6 - resulting in a total prevalence of 5%. None of the Bet v 6-positive patients showed allergic symptoms after exposure to birch pollen or an oral allergy syndrome. An increased prevalence of asthma and a higher degree of sensitization were the only distinctive clinical features in Bet v 6-positive patients.

CONCLUSIONS

Among birch pollen-sensitized patients, the prevalence of specific IgE against Bet v 6 is low. Further, sensitization to Bet v 6, which shows characteristics of a panallergen, remains clinically silent. Therefore, determination of anti-Bet v 6 is not considered useful in the clinical routine.

Management of the polyallergic patient with allergy immunotherapy: a practice-based approach

Background

The great majority (60–80 %) of patients consulting specialist physicians for allergic respiratory disease are polysensitized and thus may be potentially clinically polyallergic. However, management approaches to allergen immunotherapy (AIT) in polysensitized and polyallergic patients are not standardized.

Methods

An international group of clinicians with in-depth expertise in AIT product development, clinical trials and clinical practice met to generate up-to-date, unambiguous, pragmatic guidance on AIT in polysensitized and polyallergic patients. The guidance was developed after reviewing (1) the current stance of regulatory bodies and learned societies, (2) the literature data on single- and multi-AIT and (3) the members’ confirmed clinical experience with polysensitized patients.

Results

AIT is safe and effective in polysensitized and polyallergic patients, and should always be based on the identification of one or more clinically relevant allergens (based on the type and severity of symptoms, the duration of induced symptoms, the impact on quality of life and how difficult an allergen is to avoid). Single-AIT is recommended in polyallergic patients in whom one of the relevant allergens is nevertheless clearly responsible for the most intense and/or bothersome symptoms. Parallel 2-allergen immunotherapy or mixed 2-allergen immunotherapy is indicated in polyallergic patients in whom two causal relevant allergens have a marked clinical and QoL impact. In parallel 2-allergen immunotherapy (whether subcutaneous or sublingual), high-quality, standardized, single-allergen formulations must be administered with an interval of 30 min. Mixing of allergen extracts may be considered, as long as (1) the mixture is technically feasible, (2) the mixture is allowed from a regulatory standpoint, (3) the allergen doses are reduced in proportion to the number of components but are still at concentrations with demonstrated efficacy.

Conclusions

Physicians can prescribe AIT (preferably with high-quality, standardized, single-allergen formulations) with confidence in polysensitized and polyallergic patients by focusing on clinical/QoL relevance and safety.