**4. Sensitization**

Sensitization is the production of specific IgE antibodies to allergens and immune response begins with sensitization [3]. Asthma prevalence and incidence are affected by many factors. Allergic sensitization is one of the most important factors especially for children and adoles‐ cents [9]. Allergic sensitization increases the risk of asthma 4–20 times [23]. The effect of lifestyle factors have still been a matter of debate. On the other hand allergic disease history of the family is doubtlessly an important factor for allergic sensitization [40]. The importance of living conditions and environmental factors exposed at early childhood have been emphasised in many studies [4, 9, 22, 57].

Allergens are a kind of protein and able to penetrate the nasal and respiratory mucosa [58]. Sensitization to inhaler allergens is a major risk factor for asthma however the strength of this factor has still been debated. Furthermore, dose-response relation is another issue that has still been examined. Epidemiological evidences suggest that high level exposure to inhaler allergen is an important risk factor for atopic bronchial asthma especially in the first years of life [13, 20, 57]. It has been reported in many studies that sensitization to allergens is directly related with development of asthma symptoms, exacerbations and severity of asthma symptoms. Childhood asthma, particularly is associated with allergy sensitization and allergy exposure (**Table 1**) [13, 24, 28].

Exposure to high level allergens at early childhoods means a risk for childhood asthma. For the development of sensitization, exposure to indoor allergens at early childhood is an important determinant compared to outdoor allergens. Inner city and urban population studies have indicated that more 80% of school children with asthma sensitized to at least one indoor allergen [4, 23]. Allergic sensitization is a strong determinant for the continuity of disease at later life [40].

Skin prick test, which is the most common method to determine allergic diagnosis, is the basic test procedure to prove IgE based allergic disease sensitization. In the test different allergen extracts is pricked on upper-arm with little quantities and reaction of the person to these extracts is assessed [57]. It provides confirming the type of allergy for sensitization and different allergens can be tested simultaneously as well. The test ensures confirmation of sensitization to allergens objectively [59]. National Asthma Education and Prevention Program (NAEPP) recommends to use the test to assess exposure to allergens besides the patient's history [2]. It is helpful for specific immunotherapy since it makes right interpretation of sensitization children from the birth. As for children, the test can be re-applied if changes in symptoms or new environmental allergens are available. Experienced health professionals perform the test according to international standardized allergens. In test, ≥3 mm swolen tissue is accepted as positive allergen reaction (**Figure 1**) [58].

**Figure 1.** Skin prick test. Kwong et al. [60].

requires local national and international efforts by governments, industries and private sector

Sensitization is the production of specific IgE antibodies to allergens and immune response begins with sensitization [3]. Asthma prevalence and incidence are affected by many factors. Allergic sensitization is one of the most important factors especially for children and adoles‐ cents [9]. Allergic sensitization increases the risk of asthma 4–20 times [23]. The effect of lifestyle factors have still been a matter of debate. On the other hand allergic disease history of the family is doubtlessly an important factor for allergic sensitization [40]. The importance of living conditions and environmental factors exposed at early childhood have been emphasised in

Allergens are a kind of protein and able to penetrate the nasal and respiratory mucosa [58]. Sensitization to inhaler allergens is a major risk factor for asthma however the strength of this factor has still been debated. Furthermore, dose-response relation is another issue that has still been examined. Epidemiological evidences suggest that high level exposure to inhaler allergen is an important risk factor for atopic bronchial asthma especially in the first years of life [13, 20, 57]. It has been reported in many studies that sensitization to allergens is directly related with development of asthma symptoms, exacerbations and severity of asthma symptoms. Childhood asthma, particularly is associated with allergy sensitization and allergy exposure

Exposure to high level allergens at early childhoods means a risk for childhood asthma. For the development of sensitization, exposure to indoor allergens at early childhood is an important determinant compared to outdoor allergens. Inner city and urban population studies have indicated that more 80% of school children with asthma sensitized to at least one indoor allergen [4, 23]. Allergic sensitization is a strong determinant for the continuity of

Skin prick test, which is the most common method to determine allergic diagnosis, is the basic test procedure to prove IgE based allergic disease sensitization. In the test different allergen extracts is pricked on upper-arm with little quantities and reaction of the person to these extracts is assessed [57]. It provides confirming the type of allergy for sensitization and different allergens can be tested simultaneously as well. The test ensures confirmation of sensitization to allergens objectively [59]. National Asthma Education and Prevention Program (NAEPP) recommends to use the test to assess exposure to allergens besides the patient's history [2]. It is helpful for specific immunotherapy since it makes right interpretation of sensitization children from the birth. As for children, the test can be re-applied if changes in symptoms or new environmental allergens are available. Experienced health professionals perform the test according to international standardized allergens. In test, ≥3 mm swolen tissue

authorities [55, 56].

8 Asthma - From Childhood Asthma to ACOS Phenotypes

**4. Sensitization**

many studies [4, 9, 22, 57].

(**Table 1**) [13, 24, 28].

disease at later life [40].

is accepted as positive allergen reaction (**Figure 1**) [58].

Another sensitization test is the measuring of specific IgE antibodies for a certain antigen such as Enzyme-Linked Immunosorbent Assay (ELISA) or Radioallergosorbent test (RAST). ELISA identifies IgE with a colored reaction product whereas RAST uses radioactively labelled allergen [8, 59].


**Table 1.** Factors affecting allergic sensitization.

#### **Author details**

Ayfer Ekim

Address all correspondence to: ayferekim@hotmail.com

School of Health Sciences, Istanbul Bilgi University, Istanbul, Turkey

#### **References**


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