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Allergic Rhinoconjunctivitis
The Role of Allergen-specific Immunotherapy in the Management of
Grass-pollen-induced Allergic Rhinoconjunctivitis
Anthony J Frew
Professor of Allergy and Respiratory Medicine, Brighton and Sussex Medical School
Abstract
Allergic rhinoconjunctivitis is common and affects an ever increasing number of people. Current treatments are partially effective, but many
patients have significant residual symptoms. Allergen immunotherapy can reduce the level of clinical symptoms and prevent the
development of associated complications. Care is needed with patient selection and in the practical aspects of allergen administration.
Future trends are likely to include the use of recombinant allergens, modified allergens and adjuvants to achieve efficacy with shorter
courses of treatment and to reduce the risk of systemic side effects.
Keywords
Rhinitis, allergy, immunotherapy, T cell, future directions
Disclosure: Anthony J Frew has advised several companies with an interest in developing immunotherapies (ALK-Abello, Allergopharma, Allergy Therapeutics and Stallergenes)
and has been an investigator on numerous trials of immunotherapy and drug treatments for allergic rhinitis.
Received: 24 October 2008 Accepted: 7 May 2009
anthony.frew@bsuh.hns.uk
Grass-pollen-induced allergic rhinoconjunctivitis (or hay fever as it may be difficult to justify giving SIT. However, drug treatments
is generally called by patients) is a common clinical problem among only work for as long as they are taken, so there can be a case
children and young adults. The symptoms are fairly stereotyped and for SIT even in patients who achieve adequate control with
include itching and redness of the eyes, itchy nose, watery medication. Conversely, if the patient’s symptoms appear to be
rhinorrhoea and nasal congestion. Sometimes there is mild chest driven by a variety of allergic triggers, it is unlikely that SIT directed
tightness, especially in those with an underlying asthmatic against a single allergen will improve the situation. Therefore, each
tendency. In addition, many sufferers complain of systemic patient needs to be assessed individually and given appropriate,
symptoms, such as tiredness and irritability, although these may be tailored advice.
partially due to the side effects of medication, particularly older-
generation antihistamines. Hay fever is often mild and the SIT was developed by Noon and Freeman, from St Mary’s Hospital,
symptoms can be controlled by simple measures, such as London, and published almost 100 years ago.
1
In conventional SIT,
antihistamines used as required. A minority of patients have more which still follows the principles of Noon and Freeman, treatment is
severe symptoms, which may respond to regular prophylactic started with a low dose of allergen and the dose is then increased,
treatment with intranasal corticosteroids. However, these usually at weekly intervals over about three months, until the
treatments are not always effective. In a questionnaire survey of UK maintenance dose is achieved. Maintenance doses can then be
patients with grass pollen hay fever who were all receiving regular given at four- to six-weekly intervals for the maintenance period,
antihistamines and intranasal steroid sprays, about 30% reported which is typically three years. Sometimes patients cannot tolerate
poor symptom control, especially of the systemic symptoms. In the full maintenance dose due to side effects, in which case the
many countries, such patients would be offered desensitisation, maximum tolerated dose is given instead. Shorter regimes, given
but this is not uniformly available. each year just before the pollen season, may offer comparable
levels of benefit, at least in the short term. Whichever regime is
Specific Allergen Immunotherapy used, the benefit is partial, with patients continuing to experience
Specific allergen immunotherapy (SIT) involves the administration some symptoms, although usually much less than before their SIT.
of allergenic molecules or extracts to modify or abolish the In recent years, there has been considerable interest in alternative
symptoms of atopic allergic disease. The key features of SIT are routes of administration, especially sublingual immunotherapy.
that it offers a long-term reduction in symptoms, but its effects
are confined to the allergen that is given. Therefore, before starting Mechanisms of Specific
a patient on SIT it is essential to make an accurate diagnosis Allergen Immunotherapy
in order to identify relevant trigger factors and also to have Despite many years of research, it is still not known precisely how
tried appropriate avoidance strategies. If allergen avoidance and SIT works. Several mechanisms have been proposed, but it remains
simple drug therapy enable satisfactory control of symptoms, it unclear which of these are predictable immunological responses to
© TOUCH BRIEFINGS 2009 45
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