Allergy: research and diagnostic updates

The rise in prevalence of allergic diseases has continued in the industrialized world for more than 50 years.¹ The worldwide sensitization rates to one or more common allergens among school children are currently approaching 40 percent to 50 percent.¹ As allergy prevalence increases, so does the need to investigate effective therapies and mitigate not only patients’ suffering but the financial burden on families and societies.

This article reviews the impact of allergy and asthma, diagnostic options, “the allergy march,” and ongoing research. It also spotlights research on the effectiveness of subcutaneous and sublingual immunotherapy treatment, and new indications that vitamin D deficiency may be linked to increased risks for allergy and asthma. Vitamin D is an immunomodulator, with important effects on innate and adaptive immunity.² It has both in-utero and postnatal effects on lung development and immune system development and function, and potential mechanisms of how vitamin D can affect the risk of developing allergies and asthma have been studied.³

Definition of allergy

An allergy is a chronic, immune condition that involves an abnormal reaction to ordinarily harmless substances, called allergens. In an allergy sufferer, the immune system views the allergen as an invader and a chain reaction is initiated. White blood cells produce IgE antibodies, which attach themselves to special cells called mast cells, causing the release of potent chemicals such as histamine. These chemicals cause the familiar allergy symptoms, which can include recurrent ear infections, itching, fatigue, sneezing, nasal congestion, watery eyes, persistent cough, wheezing, gastrointestinal disorders, headaches, skin rashes, anaphylaxis and asthma.

Allergy diagnostics

Allergy-testing methods include blood tests, skin patch tests, skin injection, and the skin prick/scratch test. Allergy tests play a key role in the diagnosis and management of allergy when used in conjunction with a patient’s history of exposure and physical examination.

Blood tests (in vitro) measure the concentration of allergen-specific IgE (sIgE) in the bloodstream. With third-generation blood-allergy testing available, physicians are using this diagnostic tool as a complement to traditional skin-based testing options.

In vitro allergy testing delivers value to large-scale, track-based automation laboratory operations, as well as to clinics and physician office settings. Technology options include highly automated, analytical platforms that incorporate labor-saving efficiencies such as pre-scheduled start-up, quality control, and remote service that can perform updates and proactive troubleshooting to minimize the need for on-site system maintenance.

The allergy march

The allergy march, sometimes referred to as the atopic march,^4,5 is the typical progression of allergic diseases and often begins very early in life. The progression includes eczema. or atopic dermatitis (AD), food allergy, hay fever or allergic rhinitis, and asthma.^4-6

Allergic asthma is the most common form of asthma,⁷ which affects eight percent of adults and 10 percent of children.⁸ In the U.S., nine people die from asthma each day, and the annual cost of asthma is estimated to be $56 billion, which includes hospitalizations, pharmaceuticals and lost wages due to illness.⁹

AD is a major risk factor for the development of asthma, with an increased odds ratio reported in several longitudinal studies comparing children with and without AD. Patients with eczema with specific IgE antibodies to common environmental allergens, present by the age of two to four years, are at a higher risk for progressing in the atopic march to allergic rhinitis and asthma than those with eczema without IgE sensitization. The main risk factors for progression and persistence of asthma are early onset, IgE sensitization, and severity of AD.⁵

Ongoing allergy research                          

Allergy treatments include pharmacotherapy with antihistamines, corticosteroids, and decongestants; avoidance of food or environmental allergens that trigger an allergic reaction; and allergy shots or sublingual allergy drops to desensitize the patient to inhalant allergens. (Allergy drops are not yet approved by the FDA.)¹⁰

Johns Hopkins University researchers reviewed 142 randomized controlled studies on allergen-specific immunotherapy and summarized how well allergy shots (subcutaneous immunotherapy or SCIT) and allergy drops (sublingual immunotherapy or SLIT) work:¹⁰ In adults:

• Both allergy shots and allergy drops improve allergy and mild asthma symptoms.
• Both allergy shots and allergy drops lessen the need to take allergy and asthma medicines.
• Both allergy shots and allergy drops improve quality of life.

In children:

• Both allergy shots and allergy drops improve allergy and mild asthma symptoms.
• Allergy drops lessen the need to take allergy and asthma medicines.
• Allergy shots also appear to lessen the need to take allergy and asthma medicines, but more research is needed to confirm this.

In the last few years, the relationship between vitamin D and immune status, particularly with regard to allergy (food and environmental) and asthma, has been studied. Both cross-sectional and prospective studies have examined the effects of vitamin D on the inception and severity of allergies and asthma. Most studies have shown that low vitamin D levels increase the risk for asthma and allergies. A few suggest an increased risk with high vitamin D levels.³

Results from small, short-duration trials suggest that vitamin D supplementation decreases the severity of eczema and decreases the risk for asthma exacerbations.³ The optimal level of 25(OH)vitamin D that decreases both the risk for development and severity of allergy and asthma requires additional clinical trials before recommendations can be established.^2,3 To ensure accurate measurement, it is important to use a 25(OH)vitamin D assay that measures both 25(OH)vitamin D2 and D3 and is standardized to the ID-LC/MS/MS 25(OH)vitamin D Reference Measurement Procedure (RMP),^11,12 the reference procedure for the Vitamin D Standardization Program.

Conclusion

Early diagnosis and identification of the specific allergens that trigger allergy symptoms in each patient is essential to practice avoidance and begin immunotherapy treatment. Effective treatment may prevent the progression of allergy to asthma and improve the quality of life for both children and adults.

In vivo and in vitro studies have shown effects of vitamin D on allergy, asthma, lung function, airway responsiveness, and bronchodilator response.^2,3 Several clinical trials are underway, and results may help determine recommendations of the optimal dose of vitamin D for prevention and treatment of asthma and allergic disease.² 

References

1. Pawanker R, Canonica GW, Holgate ST, Lockey RF. World Health Organization. White Book on Allergy 2011-2012 Executive Summary. http://www.worldallergy.org/UserFiles/file/WAO-White-Book-on-Allergy_web.pdf. Accessed June 26, 2015.
2. Hoxha M,  Zoto M, Deda L, Vyshka G. Vitamin D and its role as a protective factor in allergy. http://www.hindawi.com/journals/isrn/2014/951946/. Accessed June 25, 2015.
3. Litonjua A. Vitamin D Deficiency as a risk factor for childhood allergic disease and asthma. Curr Opin Allergy Clin Immunol. 2012;12(2): 179–185.
4. American Academy of Allergy, Asthma, and Immunology. Allergic asthma. http://www.aaaai.org/conditions-and-treatments/conditions-a-to-z-search/allergic-asthma.aspx. Accessed June 26, 2015.
5. Zheng, T, Yu J, Oh MH, Zhu Z. The atopic march: progression from atopic dermatitis to allergic rhinitis and asthma. Allergy Asthma Immunol Res. 2011;3(2):67–73.
6. Wahn, U. The Atopic March. World Allergy Organization. http://www.worldallergy.org/professional/allergic_diseases_center/allergic_march/. Accessed June 26, 2015.
7. Asthma and Allergy Foundation of America. Asthma facts and figures. https://www.aafa.org/display.cfm?sub=42&id=8. Accessed June 26, 2015.
8. National Institute of Allergy and Infectious Disease. Asthma. http://www.niaid.nih.gov/topics/asthma/Pages/default.aspx. Accessed June 26, 2015.
9. United States Environmental Protection Agency. Asthma facts. http://www.epa.gov/asthma/pdfs/asthma_fact_sheet_en.pdf. Accessed June 26, 2015.
10. Agency for Healthcare Quality and Research. Allergy shots and allergy drops for adults and children: a review of the research. www.ahrq.gov. Accessed June 1, 2015.
11. Sempos CT, Vesper HW, Phinney KW, Thienpont LM, Coates PM. Vitamin D Standardization Program (VDSP.) Vitamin D status as an international issue: National surveys and the problem of standardization. Scandinavian Journal of Clinical & Laboratory Investigation. 2012;72(Suppl 243):32-40.
12. Thienpont L, Stepman HCM, Vesper HW. Standarization of measurements of 25-Hydroxyvitamin D3 and D2. Scandinavian Journal of Clinical & Laboratory Investigation. 2012;72(Suppl 243):41-49.