What is local allergic rhinitis?Local allergic rhinitis (LAR) is:
- localized nasal allergic response in the absence of systemic atopy characterized by local production of specific IgE (sIgE) antibodies
- T(H)2 pattern of mucosal cell infiltration during natural exposure to aeroallergens
- positive nasal allergen provocation test response with release of inflammatory mediators (tryptase and eosinophil cationic protein)
How common is local allergic rhinitis (LAR)?
As many as 40% of patients previously given a diagnosis of nonallergic rhinitis or idiopathic rhinitis are now being classified as having LAR.
Culprit allergens responsible include house dust mite, grass and olive pollens (in Europe), and many others.
How to diagnose local allergic rhinitis (LAR)?
Nasal allergen provocation test (NAPT) is needed to identify the culprit allergen or allergens. Neither skin prick testing nor serum sIgE antibodies are useful for diagnosis of LAR.
In a certain proportion of cases, local sIgE can be detected, and conjunctivitis, asthma, or both can be associated with LAR.
A nasal allergen provocation test with a single aeroallergen (NAPT-S) is a useful diagnostic tool in patients with LAR, with higher sensitivity than determination of nasal sIgE, tryptase, etc, However, NAPT-S with sequential application of several allergens is a very time-consuming technique.
A new protocol of NAPTs with multiple aeroallergens in one session has proved to be useful, specific, sensitive, and less time-consuming for the screening of patients with LAR. The sequential application of several aeroallergens in one session did not produce any irritant response and showed 100% concordance with the gold standard NAPT-S.
However, at this time, nasal allergen provocation test (NAPT) is not readily available at most allergy or ENT clinics. Most of the clinical diagnoses of LAR are based on history and negative skin and/or blood test.
Diagnostic approach in patients with LAR, source: J Allergy Clin Immunol. 2012 Jun;129(6):1460-7:
What is the prognosis of local allergic rhinitis (LAR)?
Good quality studies are lacking. It is not clear if patients with LAR will have systemic atopy in the future.
Further studies are needed for examine the prevalence of LAR, improve the diagnostic methods, and develop therapeutic approaches, including the use of immunotherapy.
How to treat local allergic rhinitis (LAR)?
The management of the typical allergic rhinitis includes the following:
- allergen avoidance
- pharmacologic treatment
- immunotherapy, and education.
Patients with LAR have reported a good response to topical nasal corticosteroids or antihistamines, and oral antihistamines. An important consideration is whether patients with LAR could benefit from specific treatment, such as immunotherapy, and the studies are ongoing. Birch pollen immunotherapy for local allergic rhinitis was effective in this study: http://bit.ly/2CFuaEg
Treatment Options for Allergic Rhinitis (AR) and Non-Allergic Rhinitis (NAR) (click to enlarge the image).
References:
Local allergic rhinitis: Concept, pathophysiology, and management. Rondón C, Campo P, Togias A, Fokkens WJ, Durham SR, Powe DG, Mullol J, Blanca M. J Allergy Clin Immunol. 2012 Apr 17 (PubMed).
Image source: Wikipedia, Creative Commons license.