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Year : 2022  |  Volume : 36  |  Issue : 1  |  Page : 54-59

Relevance of skin prick test, serum total immunoglobulin E, and absolute eosinophil counts in asthma patients

1 Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
2 Department of Applied Chemistry, School of Vocational Studies and Applied Sciences, Gautam Buddha University, Greater Noida, Uttar Pradesh, India

Date of Submission04-Jan-2023
Date of Acceptance05-Jan-2023
Date of Web Publication16-Feb-2023

Correspondence Address:
Dr. Raj Kumar
Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, New Delhi - 110 007
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijaai.ijaai_1_23

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BACKGROUND: Asthma is a multifaceted condition defined by chronic airway inflammation. Skin prick test (SPT), serum total immunoglobulin E (tIgE), and absolute eosinophil counts (AEC) estimation are commonly available tools for evaluating allergen sensitization.
OBJECTIVE: The present study evaluates the sensitivity to common aeroallergens and also compares serum tIgE and AEC levels with spirometry in Indian individuals with a history of allergy symptoms.
MATERIALS AND METHODS: An observational prospective study was conducted in the Outpatient Department of Viswanathan Chest Hospital, VPCI, Delhi, between 2017 and 2019. Two hundred asthma patients diagnosed as per the Global Initiative for Asthma guidelines undergo SPT against a battery of common aeroallergens and measured serum tIgE and AEC.
RESULTS: Out of 200 cases, the overall prevalence of common aeroallergens sensitization was found to be 57% (114) in asthmatic patients (atopic). SPT positivity to common aeroallergens was highest in people between the ages of 21 and 30 and lowest in people over 50. The most prevalent annoying aeroallergens were found to be weed pollens (14%), house dust mites (11%), fungi (10.5%), tree pollen (9.5%), dust (6%), kapok cotton (5.5%), grass pollen (3.5%), silk (1.5%), and wool (1%). The mean tIgE was higher in atopic asthmatic patients than in nonatopic asthmatic patients (553.25 ± 218.12 IU/ml and 489.1 ± 251.16 IU/ml; P = 0.056).
CONCLUSION: In the present study, we found that insects are the most common offending aeroallergens with higher SPT sensitivity and serum tIgE in atopic patients. Spirometry severity is not affected by allergens sensitivity in asthma patients.

Keywords: Asthma, cockroach, skin prick test, spirometry, total immunoglobulin E

How to cite this article:
Kumar M, Gupta RK, Mavi AK, Singh K, Kumar R. Relevance of skin prick test, serum total immunoglobulin E, and absolute eosinophil counts in asthma patients. Indian J Allergy Asthma Immunol 2022;36:54-9

How to cite this URL:
Kumar M, Gupta RK, Mavi AK, Singh K, Kumar R. Relevance of skin prick test, serum total immunoglobulin E, and absolute eosinophil counts in asthma patients. Indian J Allergy Asthma Immunol [serial online] 2022 [cited 2023 Mar 26];36:54-9. Available from: https://www.ijaai.in/text.asp?2022/36/1/54/369801

  Introduction Top

Allergy and asthma together affect in excess of 700 million people and place a large economic burden on health-care systems and society. Immunoglobulin E (IgE)-mediated response triggered and modulated by exposure to inhalant allergens.[1],[2] Inhaled allergens are widely known to have a key role in the etiology of asthma and other respiratory allergies.[3]

Allergens are usually protein/glycoproteins or chemically complex and low-molecular-weight substances. Other major indicators of allergenic potential include their chemical complexity, concentration, solubility, and stability in bodily fluids.[4]

Allergen exposure causes an IgE-mediated inflammatory response in allergic persons, which manifests clinically as nasal congestion, rhinorrhea, postnasal discharge, nasal itching, sneezing, and itchy or watery eyes.

Allergens such as pollen, mold, and insects are ubiquitously present in the environment and they discharge scales and other emanations from their body into the environment during their life cycle. Even after death and decay, the detritus produced also becomes airborne and comes in contact/exposure with the person who is allergic or sensitive to that substance, at that time the immune system may react excessively by start producing antibodies that directly attack the particular allergen and again this unfortunate immune response to a foreign antigen.

Skin prick testing, serum total IgE (tIgE), and absolute eosinophil counts (AEC) estimation are commonly available tools and indicators for the evaluation of allergic patients. Various studies reported a strong association between serum tIgE and AEC levels, skin prick test (SPT) sensitivity to different allergens, and allergy prevalence.[5]

This study sought to determine the prevalence of skin reactivity to various common aeroallergens, as well as explore and compare serum tIgE and AEC levels with spirometry severity in asthma patients to develop an effective therapy.

  Materials and Methods Top

A prospective observational study was carried out at the Outpatient Department of the Vallabhbhai Patel Chest Institute in Delhi in the years 2017–2018 with prior approval from the institutional ethics committee. We included 200 asthmatic patients who were diagnosed according to the 2017 Global Initiative for Asthma standards.[6] We chose asthma patients with symptoms for at least 1 year to confirm the diagnosis and rule out other possible causes based on their clinical history and physical examination. The trial excluded patients who were pregnant, lactating, or who had chronic obstructive pulmonary disease, tuberculosis, diabetes, hypertension, or heart disease. Patients' personal information, as well as information about asthma, was obtained on a usual questionnaire designed for the Indian condition.

After written consent, all enrolled patients were given an SPT for 58 common aeroallergens (i.e., 16 types of weed pollens, 11 types of tree pollens, five types of grass pollens, 12 types of fungi, five types of insects, and four types of dust, house dust mite (HDM), kapok cotton, wool, and silk antigens), pulmonary function test, and serum tIgE estimation.

Pulmonary function test

Spirometry was performed by PK Morgan using a dry, rolling-seal spirometer from the benchmark model lung function equipment (UK). The ATS recommended that maximum expiratory flow-volume curves be obtained. The forced expiratory volume in one second (FEV1)/forced vital capacity ratio was used to determine lung obstruction, whereas the FEV1 was used to estimate asthma severity.[7]

Skin prick tests

SPT was done with a battery of common aeroallergens. The allergens extract (1:10 w/v, 50% glycerinated) was procured from an Indian commercial manufacturer approved by the Drugs Controller General of India, Government of India. Glycerinated negative and positive controls were buffered saline and histamine diphosphate in a glycerinated buffer, respectively. In a nutshell, a volar aspect of the forearm was cleansed with cotton balls soaked in 70% alcohol and dried. On the forearm, a little drop of antigen was applied and each drop was numbered. The skin was then punctured with sterile needles of 26.5 gauge. The skin test reactions were assessed by calculating the mean diameter as (D + d)/2; D = biggest diameter and d = orthogonal or perpendicular diameter at the largest breadth of D after 15–20 min in comparison to the wheal size of the positive control and histamine diphosphate (10 mg/ml). The same lots of cockroach extracts were utilized in all subjects to guarantee uniformity, and only one researcher performed all SPT. According to standard Indian guidelines, a positive response (2 + and above) to a specific allergen is indicated by a mean wheal width of 3 mm or more, which is greater than the negative control (buffered saline).[8]

Absolute eosinophil counts estimation

Ethylenediaminetetraacetic acid blood (20μl) in all asthmatic patients was used to measure AEC by a hematology analyzer (Sysmex XN-1000, Japan) as per the manufacturer's instructions.

Serum total immunoglobulin E estimation

Each asthmatic patient's serum total IgE (tIgE) was determined using an enzyme-linked immunosorbent assay (ELISA) kit from Calbiotech (Calbiotech Inc., CA) and a URIT-660 microplate reader (URIT Medical Electronic Co., Ltd., Guangxi, China) according to the manufacturer's instructions. tIgE: >250 IU/ml [Male] and >175 IU/ml [Female] were considered positive.[9]

Statistical analysis

The epidemiological and therapeutic characteristics of our sample were investigated using descriptive statistics. To compare the means and significant differences between all variables in a group, an independent t-test was utilized. At a 95% confidence interval (CI), a P = 0.05 value was judged statistically significant (CI). The Statistical Package for the Social Sciences (SPSS statistics) version 16.0 was used to analyze data collected from all enrolled subjects. The data obtained from all recruited subjects were analyzed using the analysis of the data was performed by using SPSS statistical package version 16.0 for Windows (SPSS, Chicago, IL, USA).

  Results Top

Allergenic significance of common aeroallergens was evaluated by performing SPT, serum tIgE, and AEC on enrolled asthmatic patients, i.e., 81 (40.5%) were male and 119 (59.5%) females with an average age of 30.67 ± 9.93 years between 12 and 60 years. The average body mass index of the patients was 25.89 ± 5.6 kg/m2. The majority of the recruited patients came from India's Northern city, Delhi-National Capital Region, with 61 (80.5%) from urban areas and 39 (19.5%) from rural areas, with 129 (65.5%) under the age of 25 years and 71 (35.5%) under the age of 25 years. Patients with asthma for <5 years were present in 136 (68%) cases, whereas those with asthma for more than 5 years were present in 64 (32%) instances. In 121 (60.5%) of the patients, there was a family history of asthma. Breathlessness (paroxysmal 89.5% and chronic 10.5%) was the most prevalent symptom, followed by wheezing (92.5%), cough (91.5%), and nasal congestion (88%).

Overall, the seasonal variation was seen in 75.5% of the patients with aggravating factors (i.e., 7.0%, dust exposure; 5.5%, monsoon changes; 83.0%, from both) in patients [Table 1].
Table 1: Epidemiological and clinical characteristics of asthma patients

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Skin prick test pattern in asthmatic patients

Out of 200 asthmatic patients, 114 (57%) had atopic sensitivity to common aeroallergens (i.e., sensitization to at least one allergen on SPT), whereas the remaining 86 were nonatopic (43%). The skin test responses against aeroallergen antigens were observed at 166 (83%) in 1+, followed by 126 (63%) in 2+, 54 (27%) in 3+, and 40 (20%) in 4+ and above, respectively. Overall, weed pollens (28; 14%), HDM (22; 11%), fungi (21; 10.5%), tree pollen (19; 9.5%), dust (12; 6%), kapok cotton (9; 4.5%), grass pollen (7; 3.5%), silk (3; 1.5%), and wool (3; 1.5%) were found to be the most offending aeroallergens (2; 1%). The SPT pattern and grading of results (2+ and above) to a specific allergen is considered a positive reaction [Figure 1] and [Table 2].
Figure 1: Grading results of SPT asthma patients. SPT = Skin prick test

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Table 2: Skin prick test pattern in asthmatic patients

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The age group of 21–30 years had the highest SPT-positive pattern for common aeroallergens, whereas the age group >50 years had the lowest [Figure 1].

Among grass pollens (Cenchrus, Cynodon, Imperata, Pennisetum, and Sorghum), overall, 7 (3.5%) patients were SPT positive, of whom 11 (5.5%), 6 (3%), and 1 (0.5%) had reactions that were graded as +1, +2, and +3, respectively.

Among weed pollens (Asphodelus, Parthenium, Cannabis, Chenopodium Murale, Brassica, Chenopodium album, Dodonaea, Amaranthus spinosus, Xanthium, Adhatoda, Argemone, Artemisia, Suaeda, Gynandropsis, Ageratum, and Cassia occidentalis), 28 (14%) patients were SPT positive, of whom 27 (13.5%), 19 (9.5%), 8 (4%), and 1 (0.5%) had reactions that were graded as +1, +2, +3, and +4 and above, respectively.

In tree pollens (Cassia siamea, Ehretia, Eucalyptus, Kigelia, Melia, Morus, Prosopis, Putranjiva, Ricinus, Salvadora, and Holoptelia) were observed in 19 (9.5%) patients, of whom 20 (10%), 12 (6%), and 7 (3.5%) had reactions that were graded as +1, +2, and +3, respectively.

Among dust (wheat, cotton, and paper dust), 12 (6%) were observed positive in patients, of whom 5 (2.5%), 11 (5.5%), and 1 (0.5%) had reactions that were graded as +1, +2, and +3, respectively.

HDM was shown to be the third most common allergen in the research group, with 14 (7%), 11 (5.5%), 5 (2.5%), and 6 (6%) having reactions that were classified as +1, +2, +3, +4 and above, respectively.

Among the fungal spores (Aspergillus fumigatus, Aspergillus tamarii, Candida, Epicoccum, Trichoderma, Rhizopus, Alternaria, Helminthosporium, Curvularia, Cladosporium, Phoma, and Mucor), overall, 21 (10.5%) were positive, of whom 17 (8.5%), 12 (6%), 4 (2%), and 5 (2.5%) had reactions that were graded as +1, +2, +3, and +4 and above, respectively.

In our study, insects (cockroach, housefly, mosquito, rice weevil, and moth) were found the most common offending aeroallergens. Overall, 97 (48.5%) were positive, of whom 61 (30.5%), 43 (21.5%), 26 (13%), and 28 (14%) had reactions that were graded as +1, +2, +3, and +4 and above, respectively.

In other groups, kapok cotton 9 (4.5%) were positive, of whom 5 (2.5%), 8 (4%), and 1 (0.5%) had reactions that were graded as +1, +2, and +3, respectively. Similarly, in wool 2 (1%) and silk 3 (1.5%) were positive [Figure 1].

Age-wise pattern of skin prick test, total, and spirometry in asthma patients

The age group of 21–30 years had the most SPT-positive patients (n = 57; 50%), followed by 12–20 years (n = 17; 14.91%), 31–40 years (n = 26; 22.80%), 41–50 years (n = 12; 10.52%), and >50 years (n = 2; 1.75%). TIgE positivity was detected in 106 (92.98%) of SPT-positive patients, with the highest number (n = 53; 46.49%) in the 21–30 years age group, followed by 12–20 years (17; 14.91%), 31–40 years (24; 21.05%), 41–50 years (10; 8.77%), and >50 years (10; 8.77%) (2; 1.75%). Similarly, airway obstruction was found in 68 (59.64%) of all SPT-positive patients at the time of enrolment, with the largest obstruction observed in the age range 21–30 years (n = 29; 25.43%). Overall, the age group most typically impacted by all parameters is 21–30 years, with approximately half of all patients falling into this category [Figure 1].

Atopic and nonatopic patients' total immunoglobulin E, absolute eosinophil counts, and spirometry patterns

TIgE levels were found to be elevated in 178 (89%) asthma patients. It was substantially greater in atopic asthma patients (106 vs. 72; P = 0.049) than in nonatopic asthma patients. The mean serum tIgE was found high in atopic patients as compared with nonatopic patients (553.25 ± 218.12 and 489.1 ± 251.16 IU/ml; P = 0.056). The AEC level was found almost same in the both atopic and nonatopic patients (P = 0.662). Overall, 68 (59.7%) atopic and 58 (67.4%) nonatopic asthma patients had airway obstruction, which was not statistically significant (P = 0.0.258) [Table 3] and [Figure 2].
Figure 2: Age-wise distribution of SPT, tIgE, and PFT (Obstruction). SPT = Skin prick test, tIgE = Total Immunoglobulin E, PFT = Pulmonary function test

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Table 3: Serum total immunoglobulin E eosinophil and spirometry pattern in atopic and nonatopic patients

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  Discussion Top

Aeroallergens are significant in the development of respiratory allergic disorders.[10] In the diagnosis and treatment of asthma and allergic rhinitis (AR), determining the most common aeroallergens to which patients are allergic is critical. Skin allergy testing has long been regarded as the "gold standard" approach for demonstrating antigen sensitization. The SPT was discovered to be more sensitive and specific than the radioallergosorbent test.[11] The types of aeroallergens, on the other hand, vary greatly depending on location and even within and between countries.[12]

In the present study, overall, 114 (57%) patients exhibited positive sensitization against common aeroallergens were graded as 166 (83%) in 1+, followed by 126 (63%) in 2+, 54 (27%) in 3+, and 40 (20%) in 4+ and above, respectively. Skin testing remains a practical and sensitive indicator of IgE antibody response, verification of its specificity is required by measuring the specific IgE antibodies in the patient's sera using in vitro procedures, such as radioallergosorbent test and ELISA. The advantages of these methods for the diagnosis of allergy are convenience for the patient, no patient risk, not influenced by drugs, allergen is stable in solid phase state for a long time, preferable to skin testing in infants, patients with dermographism and patients with widespread dermatitis, and good correlation with endpoint skin test titration, clinical severity of disease, and histamine release studies.[13] In the present study, the specificity of skin reactions was also determined by performing serum tIgE.

In a similar study conducted by us at the Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India, in 1997–2000, we discovered that 29.03% of patients with bronchial asthma (BA) and/or AR have no allergic component, 19.35% have grades of 1 + to some of the antigens tested, and 51.62% have a significant skin positive reaction using the intradermal skin test method. Ghaffari et al. observed that SPT was positive in 156 (41.5%) patients with BA and/or AR in an Iranian study.[14] In a retrospective cross-sectional study, Almogren discovered that SPT was positive in 75% of individuals with respiratory allergies such as BA and/or AR.[15] Farhoudi et al. recently published a cross-sectional retrospective analysis of patients with similar diagnoses that found substantial positive SPT reactivity in 154 (68%) of the participants.[16]

Young males and adult females are more susceptible to allergen sensitivity; however, the explanation for this is unknown. Depending on the lifestyle of the population groupings, differences in age and gender distribution may be linked to varied allergen exposure. Overall, allergen sensitivity was detected in 114 (57%) asthmatic patients (atopic), with the highest prevalence among those aged 21–30 years. Similarly, with approximately 50% of cases, serum tIgE was found to be highest in the same age group. Wang et al. found that the prevalence of aeroallergen sensitization reduced with age, similar to our findings.[17] According to Ghaffari et al., allergen SPT reactivity increases in the middle age group and subsequently decreases with age.[14] Younger adults were the most typically afflicted age group, according to Kumar et al.[12] Exposure duration, work, lifestyle, and genetic vulnerability may all play a role in the higher prevalence of sensitivity in children. Patients with greater blood eosinophil counts had more asthma episodes than those with lower eosinophil counts; however, the amount of eosinophil in both atopic and nonatopic asthmatic patients was nearly the same in our study.[18]

The release of interleukin, which is triggered by the intake of a specific allergen, is a defining feature of allergic asthma (or atopic), resulting in the production of specific antibodies in those who are vulnerable.[19] As a result, the presence of particular antibodies in the serum is the primary indicator of allergic asthma.[20] A study found a relationship between allergen exposure in the first 3 months of life and the development of recurrent wheeze in the 1st year of life in newborns in urban areas.[21] Similarly, atopic asthmatic patients had greater blood tIgE against antigens, according to our findings. This research reveals that allergen exposure is a key risk factor for allergic disease aggravation and symptom development. Hence, preventive exposure to sensitive allergens may be helpful in the control of diseases among atopic asthma (allergic). If symptoms continue or avoidance is impossible, immunotherapy with a specific allergen can be regarded as an effective treatment.

  Conclusion Top

In the present study, we found that insects are the most common offending aeroallergens with higher SPT sensitivity and serum tIgE in atopic patients. Spirometry severity is not affected by allergens sensitivity in asthma patients. In this study, the amount of eosinophil in both atopic and nonatopic asthmatic patients was almost the same, despite the fact that patients with higher blood eosinophil counts had more asthma episodes than those with lower eosinophil counts.

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3]


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