Po PolskuDepartment of Allergology & Internal Diseases, University Medical School, Bialystok, Poland
Published in: R. Spiewak (Editor): "Pollens and Pollinosis: Current Problems". Institute of Agricultural Medicine, Lublin (Poland) 1995, page 93.
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The hyposensitisation, now called specific immunotherapy (sIT), was introduced in 1911 by Noon and Freeman for the treatment of patients with pollen rhinitis. Despite such a long tradition sIT remains a very controversial method of therapy, and even now it is not generally accepted. The reasons for this may be found in the lack of scientific bases of sIT, poor knowledge of the underlying mechanisms of both allergic reactions and the action of immunotherapy, and consequently lack of possibility of objective control of the effects of treatment and the frequent occurrence of undesirable symptoms. Without doubt the use of badly purified, nonstandardized allergen extracts played a role in this.
In 1993 a team of experts of EAACI Immunotherapy Subcommittee published the second edition of the Immunotherapy Position Paper, describing the progress in studies of allergic processes and specific immunotherapy mechanisms made in recent years. The Position Paper also gave many practical directions, which can be useful in allergological practice.
According to the majority of allergologists, sIT is still believed to represent an effective and causal treatment of IgE-mediated allergic diseases. The use of sIT in venom and pollen allergy is generally accepted. Pollinosis seems to be a good model for study of the local and systemic allergic process and for evaluating the influence of sIT on this disease.
In considering the direction of sIT action one should take into account: its influence on humoral immunity (IgE, allergen specific IgE and IgG4, anti-IgE), cellular immunity (activity and accumulation of effector cells and release of allergo-inflammatory mediators), and generation of the late allergic reaction phase with participation of eosinophils, neutrophils, basophils and T cells, in particular Th2. As studies in recent years have shown, sIT influences change in the differentiation of subpopulation Th2 into Th1, which is of great importance in the formation of the cytokine release profile and in limiting the two-phase allergic reaction. The Th2 cells are responsible for production of cytokines such as: IL-3, IL-4, IL-10, which play a significant role in the development of the late allergic reaction, whereas Th1 cells produce INF-γ and IL-2, which act antagonistically to cytokines produced by Th2 cells.
At present the characteristic feature of successful sIT is considered to be its ability to inhibit the late allergic reaction induced by the allergen, as has been confirmed in studies of this reaction in the skin, bronchial tree and lately also in the nasal mucosa.
The lecture will also present the clinical results of some studies from the literature and our own experience in sIT in pollinosis, and the future of immunotherapy using recombinant allergens and synthetic peptides, including the major epitopes of given allergens, making safe and effective suppression of specific IgE and inactivation of allergen-specific Th cells possible.
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