Sublingual immunotherapy

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Sublingual Immunotherapy is method of allergy treatment that uses an allergen solution given under the tongue, which over the course of treatment, reduces sensitivity to allergens. Sublingual immunotherapy, or SLIT, has a very good safety profile and is given at home in adults and children.[1] The basis of sublingual immunotherapy is treatment the underlying allergic sensitivity. Allergic symptoms improve as the allergic sensitivity improves. As a safe and effective method of treating the underlying disease, sublingual immunotherapy is capable of modifying the natural progression of allergic disease which can begin with allergic food sensitivities and eczema in young children and progress through allergic rhinitis and asthma in older children and adults.[citation needed]

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[edit] Mechanism

Sublingual immunotherapy is taken as drops under the tongue of a specific allergen solution which interacts with the immune system to decrease allergic sensitivity. Commonly the drops are taken one to three times a day and held under the tongue for 30 seconds. The antigen persists on the mucosal surface and is taken up by dendritic cells which interact with T lymphocytes (T-cells).

Sublingual immunotherapy takes advantage of immunologic tolerance of the oral mucosa to non-pathogenic antigens such as foods and resident bacteria. Consider the vast number of antigens we are exposed to every day which do not illicit an allergic response. Dendritic cells in the oral mucosa act as antigen presenting cells (APC) to T-cells in the cervical lymph nodes. This system modulates the allergic response by creating immune tolerance to antigens. The sublingual mucosa has few pro-inflammatory cells, such as mast cells, which would provoke an allergic reaction. This explains in part the safety margin of sublingual therapy.

Early in treatment, sublingual dendritic cells secrete interleukin 10 (IL-10) which induces regulatory T cells to inhibit the inflammatory response.[2] Long term changes that occur with immunotherapy include the formation of IgG which acts to block IgE and modulates the TH2 response. With sublingual immunotherapy there is a decrease in the IgE/IgG4 and a decrease in the TH2/TH1 ratio.[2] and Freeman in 1911. The oral route of immunotherapy was suggested earlier in 1900 [3] although the first clinical attempts were not made until the 1920s.[4] Clinical use of sublingual immunotherapy for foods was described in 1969 by David Morris[5] and in 1970 for inhalant allergens.[6] Although patients treated for food, pollen, pet dander and mold allergy by sublingual immunotherapy improved, the mechanism of why it was effective was not apparent and few studies were published in peer reviewed journals. The practice of sublingual immunotherapy remained an alternative therapy until controlled clinical trials and advances immunology showed the validity of this method.

While the practice of sublingual immunotherapy has been more available in Europe than in the United States, it was not until concerns regarding the risks of injection immunotherapy including deaths from anaphylaxis[7] were published in the 1980’s that formal research into alternatives to injection therapy was supported. Pioneering studies in Europe demonstrating the safety and effectiveness of sublingual immunotherapy and fostered international acceptance of the method. In 1998 the World Health Organization concluded that sublingual immunotherapy was a viable alternative to the injection route and that its use in clinical practice is justified.[8] Public acceptance facilitated the publication of new research. Between 1990 and 2005 more than 40 controlled trials with non-injection routes were published in peer-reviewed journals.[9] Today in Europe, sublingual immunotherapy accounts for 40 percent of allergy treatment. In the United States, sublingual immunotherapy is gaining support among traditional allergists and is endorsed by otolarygologists who practice allergy treatment.

[edit] Comparison to other allergy management regimens

Options for managing allergy include avoiding what you're allergic to, such as not eating a food you have a known problem with, avoiding pets, etc. Many allergens are unavoidable due to the widespread nature of dust, molds, pollens, weeds, and various food elements in packaged and processed foods.

Of course there are many over the counter medications such as antihistamines, prescription oral medication and nasal and oral sprays or inhalers. These allergy medications treat the symptoms of allergy, not the cause. Allergy immunotherapy is the only treatment directed at resolving the underlying cause of allergy symptoms.

Currently, immunotherapy is offered via allergy shots, or sublingual immunotherapy (allergy drops). Like allergy shots, sublingual immunotherapy directly changes the body’s ability to react with allergens. Following successful desensitization with immunotherapy, allergy symptoms when exposed to known allergies or antigens should be reduced or completely absent.

The biggest difference between allergy shots and sublingual immunotherapy is how the allergy serum is delivered to the patient. Both methods use a serum which is an extract of an offending allergen, such as an extract of ragweed pollen. This extract has the ability to “vaccinate” you against your allergies.[citation needed]

Following a test of your allergies either by skin testing or more modern blood IgE testing, a specific profile of antigen extracts can be mixed and offered for immunotherapy. With sublingual immunotherapy, one places drops of serum under the tongue on a daily basis.

Benefits of the treatment include convenience, safety, affordability, no time-consuming visits to a doctor’s office once or twice per week for injections, and the ability to treat a broader range of patients and allergens.

[edit] Side Effects

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Sublingual immunotherapy is noted as a safer alternative to allergy injections. There has not been a life-threatening reaction recorded with the sublingual drops making it safe to use at home. Within 8 months, patients typically note symptom relief. Within three to five years of allergy sublingual immunotherapy, most patients can be desensitized, though this depends on the severity and complexity of patients' allergies. Some local sensitivities have been reported (minor oral itching) but can be controlled through dose adjustment. [10]

[edit] References

  1. ^ Gidaro G, Marcucci F, Sensi L, Incorvaia C, Frati F, Ciprandi G (2005). "The safety of sublingual-swallow immunotherapy: an analysis of published studies". Clin Exp Allergy 35 (5): 565-71. PMID 15898976. 
  2. ^ a b Moingeon P, Batard T, Fadel R, Frati F, Sieber J, Van Overtvelt L (2006). "Immune mechanisms of allergen-specific sublingual immunotherapy". Allergy 61 (2): 151-65. PMID 16409190. 
  3. ^ Curtis HH. (1900) The immunizing cure of hayfever. Med News (NY);77:16-8.
  4. ^ Black JH. (1927) The oral administration of pollen. J Lab Clin Med;12:1156
  5. ^ Morris D (1969). "Use of sublingual antigen in diagnosis and treatment of food allergy". Ann Allergy 27 (6): 289-94. PMID 5785921. 
  6. ^ Morris D (1970). "Treatment of respiratory disease with ultra-small doses of antigens". Ann Allergy 28 (10): 494-500. PMID 5521180. 
  7. ^ Reid M, Lockey R, Turkeltaub P, Platts-Mills T (1993). "Survey of fatalities from skin testing and immunotherapy 1985-1989". J Allergy Clin Immunol 92 (1 Pt 1): 6-15. PMID 8335856. .
  8. ^ Bousquet J, Lockey R, Malling H (1998). "Allergen immunotherapy: therapeutic vaccines for allergic diseases. A WHO position paper". J Allergy Clin Immunol 102 (4 Pt 1): 558-62. PMID 9802362. 
  9. ^ Canonica G, Passalacqua G (2003). "Noninjection routes for immunotherapy". J Allergy Clin Immunol 111 (3): 437-48; quiz 449. PMID 12642818. 
  10. ^ Passalacqua G, Guerra L, Pasquali M, Lonbardi C, Canonica G (2004). "Efficacy and safety of sublingual immunotherapy". Annals of Allergy, Asthma & Immunology 93: 3-12. PMID 16409190. 

[edit] External links

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