Diana Birch, BSc (Hons), RN, DipAsthma;Andrew Williams, RN, DipAsthma.
Diana-formerly Clinical Research Nurse (Allergy and ENT), National Heart and Lung Institute, London; Andrew-Allergy Research Nurse, Homerton University Hospital, LondonImmunotherapy, also called desensitisation or allergy vaccination, is usually undertaken with a series of injections that help the body to gradually build 'immunity' to allergens. Although used world-wide, allergy vaccination is limited in the UK (apart from for research purposes) to bee and wasp venom and grass pollen allergies.
Patients with severe seasonal allergic rhinitis caused by grass pollen that is unresponsive to other treatments may be candidates for immunotherapy. A detailed patient history is required. See the Factfile on allergic rhinitis, page 403.
Although patient satisfaction with symptom improvement rates is not always recorded, there are suggestions that 70 to 80% of patients were satisfied or very satisfied with treatment (Frank et al, 2001). A recent study showed that symptoms can be reduced by 50%, need for medication reduced by 80% and seasonal chest symptoms reduced by 90% (Walker et al, 2001).
Patients receive a weekly subcutaneous injection for the first few months of conventional immunotherapy. The first injection is a very dilute solution of the vaccine. The concentration is gradually increased each week for several months, according to a predetermined schedule that can be modified to suit the patient's tolerance. Usually the highest concentration, or maintenance dose, is reached four to six months into immunotherapy. A maintenance dose is then given every one to two weeks and then extended to every three or four weeks. The course lasts three years to produce optimum benefit (Durham et al, 1999).
Immunotherapy should be performed only by appropriately trained staff in specialist centres with immediate access to resuscitation equipment, according to the international consensus report on diagnosis and management of asthma (WHO, 1992). It is contraindicated in patients with perennial asthma because they are more likely to develop severe adverse reactions (Frew, 1993).
Local reactions at the injection site (swelling/itch) are common and to be expected. With 'modified' allergen immunotherapy it is thought that severe reactions are less likely to occur because the pollen is washed in a chemical that reduces its allergenicity.
There are two main products that are used in the UK:
Immunotherapy is effective and safe when carried out by properly trained and equipped health professionals on patients who have been carefully selected and screened. Access to these treatments is limited because, although allergy has a high profile with the public, this has yet to translate into adequate service availability.
British Allergy Foundation, Deepdene House, 30 Bellegrove Road, Welling, Kent DA16 3PY. Helpline: 020-83038583. www.allergyfoundation.com
Durham, S.R., Walker, S.M., Varga, E.M. et al. (1999) Long-term clinical efficacy of grass pollen immunotherapy. New England Journal of Medicine 341: 468-475.
Frank, E., Williams, A., Cromwell, O. et al. (2001) Effectiveness of a pre-seasonal allergoid immunotherapy in patients with seasonal allergic rhinitis due to grass pollen (abstract). Journal of Allergy and Clinical Immunology 107: 2, 260.
Frew, A.J. (1993) Immunotherapy (British Society of Allergy and Clinical Immunology working party). British Medical Journal 307: 919-923.
Resuscitation Council UK. (2002) Emergency Medical Treatment of Anaphylactic Reactions for First Medical Responders and for Community Nurses. London: RCUK.
Walker, S.M., Pajno, G.B., Lima, M.T. et al. (2001) Grass pollen immunotherapy for seasonal rhinitis and asthma: a randomized, controlled trial. Journal of Allergy and Clinical Immunology 107: 1, 87-93.
World Health Organization. (1992) International consensus report on the diagnosis and management of asthma: international management project. Allergy 47: 1-61.