Specific
immunotherapy consists of the administration of
allergen extracts to patients with allergic disease to achieve clinical tolerance to the causative
allergens. Currently, it is the only etiologic treatment for respiratory
allergy. A World Health Organization opinion paper published in 1997 defines
immunotherapy as "the only form of treatment able to modify the natural course of allergic diseases". In patients with
allergic rhinitis, several studies suggest that
immunotherapy can modify the natural history of respiratory
allergy by preventing the development of
asthma in children with this disease. Numerous studies demonstrate its efficacy in
IgE-mediated
asthma and particularly in mild-to-moderate
asthma. When complete avoidance of the
allergen cannot be achieved with measures that allow the patient to lead a normal life, pharmacological treatment can help to control symptoms, but symptoms immediately return when treatment is interrupted. However,
asthma care can be improved by
allergen-specific treatment;
immunotherapy may shift the immune response from an allergic pattern toward a more protective response, producing persistent improvement with reduction of symptoms and the need for pharmacological treatment. Numerous comparative studies with specific
immunotherapy vs. placebo or pharmacological treatment have demonstrated the efficacy of this treatment and its advantages in control of the disease. Specific
immunotherapy induces favorable clinical,
biological and functional modifications in the course of allergic
asthma. Significant improvement in clinical manifestations has been demonstrated, even with levels of
allergen exposure higher than those at the beginning of treatment. This improvement is associated with a reduced need for antiinflammatory and
bronchodilator treatment. Moreover, specific bronchial reactivity shows a clear improvement with disappearance of delayed response and a clear increase in the threshold for immediate response to the
allergen. Reduction in nonspecific
bronchial hyperreactivity and improvement in
exercise-induced asthma are also observed. Several studies recommend an optimal duration of specific
immunotherapy for allergic
asthma of between 3 and 5 years to achieve maximal therapeutic efficacy. A direct relationship between
treatment duration and the persistence of its effects has been observed. Moreover, the treatment is more effective when started early. The possible adverse effects related to systemic reactions should be borne in mind. Although these effects are infrequent, maximal precautions should be taken when administering this treatment.
Immunotherapy is contraindicated in cases of severe
asthma,
heart disease,
autoimmune disease and associated severe
neoplastic processes. However, all the beneficial effects of
immunotherapy are conditioned by an accurate and early etiological diagnosis confirming the causative
allergen. The availability of high-quality
allergen extracts is essential to obtain the desired effect. Inappropriate patient selection for this treatment is the main cause of its failure. The integral treatment of allergic
asthma includes environmental measures, patient education, pharmacological treatment and, whenever possible,
immunotherapy.