Allergen Immunotherapy
Allergen immunotherapy is a desensitisation process for IgE-mediated hypersensitivity to common allergens such as pollens, HDM and insect venoms. It is the only disease-modifying treatment available for AR. 17 The administration of high-dose allergen, using sublingual (SLIT) or subcutaneous (SCIT) immunotherapy, suppresses the pro-allergic dendritic cell phenotype by inducing T-cell differentiati
Allergen immunotherapy is a desensitisation process for IgE-mediated hypersensitivity to common allergens such as pollens, HDM and insect venoms. It is the only disease-modifying treatment available for AR.17
The administration of high-dose allergen, using sublingual (SLIT) or subcutaneous (SCIT) immunotherapy, suppresses the pro-allergic dendritic cell phenotype by inducing T-cell differentiation to regulatory phenotypes (Tregs). Induction of B regulatory cells to stimulate blocking antibodies further reduces mast cell degranulation.63
Allergen immunotherapy improves short- and long-term symptom severity, decreasing the need for medication for AR and protecting against the progression from AR to asthma.64,65,66 Allergen immunotherapy studies have further demonstrated a reduced need for asthma medications67 and a reduction in new aeroallergen sensitisations.65
Subcutaneous and SLIT are both effective once the causative allergen has been accurately identified by history and allergen sensitisation tests. Allergen provocation tests might be necessary in cases of high suspicion and inconclusive allergy test results.57,68 According to the ARIA-EAACI care pathway, both monosensitised (single dominant antigen) and polysensitised (multiple antigens) patients can benefit.57,68
Patients who should be considered for AIT include the following:
- Those in whom symptom control is not achieved with pharmacotherapy and allergen avoidance.
- Those in whom high medication doses with potential side effects are required, particularly corticosteroids.
- Those in whom adverse events have occurred on normal doses of pharmacotherapy.
- Those who would prefer not to have to take pharmacotherapy for prolonged periods.
- Children in whom AIT would potentially be a modifying intervention to prevent further sensitisations and to reduce the chance of developing asthma.
- Potentially adolescents or adults with pollen-food syndrome.
The duration of treatment should be for at least 3 years but needs to be individualised and might need to be continued for up to 5 years according to symptom severity and control.69
Asthma should be well controlled, and practitioners should be well versed in the management of adverse events, including rare cases of anaphylaxis.70,71
Currently, acquisition of AIT is made difficult by the fact that it is an expensive, unlicensed product with a single distributor in South Africa. For greater access, it would be preferable for products to be registered with the SA Health Products Regulatory Authority (SAHPRA). The acquisition cost of AIT is high, but the reduction in morbidity and medication costs makes it cost-effective.
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Richards GA, McDonald M, Gray CL, et al. Allergic rhinitis: Review of the diagnosis and management: South African Allergic Rhinitis Working Group. S Afr Fam Pract. 2023;65(1), a5806. https://doi.org/10.4102/safp.v65i1.5806