Ragweed sublingual tablet immunotherapy: part II - practical considerations and pertinent issues

Diverse and highly cross-reactive T-cell responses in ragweed allergic patients independent of geographical region

BACKGROUND

Ragweed frequently causes seasonal allergies in North America and Europe. In the United States, several related ragweed species with diverse geographical distribution cause allergic symptoms. Cross-reactivity towards related ragweed species of IgE and treatment-induced IgG₄ has been demonstrated previously. However, less is known about the underlying T-cell cross-reactivity.

METHODS

The allergen content of ragweed extracts was determined by mass spectrometry and related to T-cell epitopes of Amb a allergens (group 1, 3, 4, 5, 8 and 11) in 20 American ragweed allergic patients determined by FluoroSpot and proliferation assays. T-cell responses to 50 frequently recognized Amb a-derived T-cell epitopes and homologous peptides from western ragweed (Amb p), giant ragweed (Amb t) and mugwort (Art v) were investigated in an additional 11 American and 14 Slovakian ragweed allergic donors.

RESULTS

Ragweed extracts contained all known allergens and isoallergens thereof. Donor T-cell responses were diverse and directed against all Amb a 1 isoallergens and to most minor allergens investigated. Similar response patterns were seen in American and Slovakia donors. Several epitopes were cross-reactive between isoallergens and ragweed species, some even including mugwort. T-cell cross-reactivity generally correlated with allergen sequence homology.

CONCLUSION

T-cell epitopes of multiple allergens/isoallergens are involved in the diverse T-cell responses in ragweed allergic individuals. T-cell lines were highly cross-reactive to epitopes of related ragweed species without any apparent geographical response bias. These data support that different ragweed species can be considered an allergen homology group with Amb a as the representative species regarding diagnosis as well as allergy immunotherapy.

Adherence During Early Allergen Immunotherapy and Strategies to Motivate and Support Patients

Allergic rhinitis is one of the most common chronic inflammatory conditions, affecting up to 30% of people in Europe. Allergen immunotherapy (AIT) is the only treatment for allergic rhinitis and asthma that has a disease-modifying effect, and it is recommended in European guidelines for use in conjunction with patient education, specific allergen avoidance, and symptomatic pharmacotherapy. Reported AIT adherence rates vary widely but are often low in real-world settings. Factors known to affect adherence are patient, treatment, or physician-related, and vary between healthcare settings. Misconceptions or a lack of AIT knowledge among patients with regard to efficacy and side effects may contribute to high rates of discontinuation observed during the first year of AIT treatment. Interventions to improve patient adherence are multifaceted and should focus on patient education, particularly the provision of accurate information regarding adverse effects of AIT and when to expect an improvement in symptoms, patient-support programmes, and the use of regular eHealth reminders via a telephone call, text message, or social media. Serum-based biomarkers also have the potential to play a role in evaluating early response to AIT and in monitoring treatment adherence in clinical practice. In this review, the authors explore barriers to continuation with AIT and discuss initiatives to motivate and support patients through the challenging early months of treatment, prior to the onset of clinical effect and when side effects are most common, to encourage long-term adherence to therapy and achieve optimal patient outcomes.