Prevalence of allergic sensitization to inhalant allergens among blood donors in Kuwait--a desert country

Associations between HLA class II alleles and IgE sensitization to allergens in the Qatar Biobank cohort

Background

Allergic disorders are the consequence of IgE sensitization to allergens. Population studies have shown that certain human leukocyte antigen (HLA) alleles are associated with increased or decreased risk of developing allergy.

Objective

We aimed to characterize the relationship between HLA class II allelic diversity and IgE sensitization in an understudied Arab population.

Methods

We explored associations between IgE sensitization to 7 allergen mixes and mesquite (comprising 41 food or aeroallergens) and 45 common classical HLA class II alleles in a well-defined cohort of 797 individuals representing the general adult population of Qatari nationals and long-term residents. To do so, we performed HLA calling from whole genome sequencing data at 2-field resolution using 2 independent algorithms. We then applied 3 different regression models to assess either each allergen mix independently, in the context of IgE sensitization to other allergens tested, or polysensitization.

Results

More than half (n = 447) of the study participants showed IgE sensitization to at least 1 allergen, most of them (n = 400) to aeroallergens (Phadiatop). We identified statistically significant negative and positive associations with 24 HLA class II alleles. These have been reported to confer risk or protection from variety of diseases; however, only a few have previously been associated with allergy in other populations.

Conclusions

Our study reveals several new risk and protective genetic markers for allergen-specific IgE sensitization. This is a first and essential step toward a better understanding of the origins of allergic diseases in this understudied population.

Airborne pollen calendar of Portugal: a 15-year survey (2002-2017)

INTRODUCTION

Data about the occurrence of airborne pollen enables the creation of pollen calendars with an approximation of flowering periods for the most common allergenic plant species in a specific area. The aim of this work is to provide pollen calendar for each of the seven monitoring regions of Portugal based on 15 years of airborne sampling, in order to chart the seasonal behaviour of the main allergenic pollen types.

MATERIAL AND METHODS

Airborne pollen monitoring (2002-2017) was carried out by the Portuguese Aerobiology Network (RPA), using Hirst-type volumetric spore traps, following well-established guidelines.

RESULTS

A total of 14 airborne pollen types were recorded at RPA monitoring stations, of which 64.2% belong to trees, 28.5% to herbs and 7.1% to weeds. The airborne pollen spectrum is dominated by important allergenic pollen types such as Poaceae, Quercus spp., Urticaceae and Cupressaceae. The average pollen index was 42.557 in mainland Portugal and 3.818 in the Islands. There was an increased trend in the airborne pollen levels over the years, namely in Coimbra, Évora and Porto, compared to the remaining regions.

CONCLUSION

This report provides accessible information about the main allergenic airborne pollen types occurring in the course of the year. The pollen calendars charted for each Portuguese region showed that the occurrence of most allergenic taxa was centred from March to July. Pollen peak concentrations were detected earlier in the Centre and Lisbon and Tagus Valley regions, and later in the remaining regions.

The most common aeroallergens in a tropical region in Southwestern Iran

Background

Respiratory allergies are the most important public health issues in the world. They are caused by aeroallergens which play great role in pathogenesis of respiratory allergic diseases.

Methods

The current study was conducted to evaluate the prevalence of positive skin test for various aeroallergens among allergic patients in Ahvaz, southwest Iran. 299 participants with allergic rhinitis (seasonal or perennial) were selected. Skin prick test using twenty three common allergen extracts was performed on all patients.

Results

The overall frequency of sensitization to any allergen was 85.6%. In outdoor allergens the most prevalent aeroallergen category was weeds (89%) followed by tree and grasses, and in indoor allergens, mites (43%) were the most prevalent aeroallergen. The mean and median numbers of positive test reactions among those with positive test responses were 11.5 and 13.0, respectively. 84% of patients were poly-sensitised and about 50% of them were sensitised to more than twelve different allergens.

Conclusion

The results of the study revealed that prevalence of the skin prick reactivity to weed pollens is significant in southwest Iran and multiple sensitizations were common.

Chenopodium album pollen profilin (Che a 2): homology modeling and evaluation of cross-reactivity with allergenic profilins based on predicted potential IgE epitopes and IgE reactivity analysis

The inhalation of Chenopodium album (C. album) pollen has been reported as an important cause of allergic respiratory symptoms. The aim of this study was to produce the recombinant profilin of C. album (rChe a 2) pollen and to investigate its cross-reactivity with other plant-derived profilins based on potential conformational epitopes and IgE reactivity analysis. Che a 2-coding sequence was cloned, expressed, and purified using one step metal affinity chromatography to recover high-purity target protein. We assessed cross-reactivity and predicted IgE potential epitopes among rChe a 2 and other plant-derived profilins. Immunodetection and inhibition assays using sixteen individual sera from C. album allergic patients demonstrated that purified rChe a 2 could be the same as that in the crude extract. The results of inhibition assays among rChe a 2 and other plant-derived profilins were in accordance with those of the homology of predicted conserved conformational regions. In this study, amino acid sequence homology analysis showed that a high degree of IgE cross-reactivity among plant-derived profilins may depend on predicted potential IgE epitopes.

Cloning and expression of Che a 1, the major allergen of Chenopodium album in Escherichia coli

Chenopodium album is a weedy annual plant in the genus Chenopodium. C. album pollen represents a predominant allergen source in Iran. The main C. album pollen allergens have been described as Che a 1, Che a 2, and Che a 3. The aim of this work was to clone the Che a 1 in Escherichia coli to establish a system for overproduction of the recombinant Che a 1 (rChe a 1). In order to clone this allergen, the pollens were subjected to RNA extraction. A full-length fragment encoding Che a 1 was prepared by polymerase chain reaction amplification of the first-strand cDNA synthesized from extracted RNA. Cloning was carried out by inserting the cDNA into the pET21b+ vector, thereafter the construct was transformed into E. coli Top10 cells and expression of the protein was induced by IPTG. The rChe a 1 was purified using histidine tag in recombinant protein by means of Ni-NTA affinity chromatography. IgE immunoblotting, ELISA, and inhibition ELISA were done to evaluate IgE binding of the purified protein. In conclusion, the cDNA for the major allergen of the C. album pollen, Che a 1, was successfully cloned and rChe a 1 was purified. Inhibition assays demonstrated allergic subjects sera reacted with rChe a 1 similar to natural Che a 1 in crude extract of C. album pollen. This study is the first report of using the E. coli as a prokaryotic system for Che a 1 cloning and production of rChe a 1.

Date Palm Pollen Allergoid: Characterization of Its Chemical-Physical and Immunological Properties

BACKGROUND

Date palm (DP) pollen can cause allergic symptoms in people living in different countries. Specific immunotherapy with allergenic extracts by subcutaneous route is effective to cure allergic people. However, the risk of side effects has led to explore safer therapeutic modalities. The aim of our work was to evaluate IgE cross-reactivity between DP and autochthonous palm (European fan palm, EFP) pollen extracts, to chemically modify DP extract with potassium cyanate in order to obtain an allergoid, and to characterize it.

METHODS

By radioallergosorbent test inhibition, immunoblotting (IB) and skin prick test, in vitro and in vivo allergenic activities of native and modified DP extracts were compared. By SDS-PAGE and IB, we compared the protein profile and IgE-binding capacity of both native and modified DP, as well as of EFP extracts. By IB inhibition, IgE cross-reactivity of native DP and EFP extracts was evaluated. By ELISA, the capacity of modified DP-induced IgG to react with native DP extract was determined.

RESULTS

Radioallergosorbent test inhibition, IB and skin prick test results demonstrated that modified DP was significantly less allergenic than native DP extract. The SDS-PAGE profile showed that potassium cyanate treatment of DP extract did not alter the molecular weight of its components. In addition, no difference was observed between native DP and EFP extracts. Subsequent IB inhibition data evidenced the existence of a strong IgE cross-reactivity between native DP and EFP extracts. ELISA results indicated that the administration of modified DP in mice was able to induce specific IgG also recognizing native DP extract.

CONCLUSIONS

Modified DP extract (allergoid) seems to be a good candidate for immunotherapy of patients affected by specific allergy.

Emerging pollen allergens

Numerous pollen allergens have been reported over the last few years. Most of them belong to well-known families of proteins but some others constitute the first member of new allergenic families. Some of the factors that can contribute to the detection and identification of new pollen allergens are: a) advances in the technology tools for molecular analysis; and b) the deep knowledge of many allergenic sources. The combination of these factors has provided vast information on the olive pollen allergogram and the identification of minor allergens that become major ones for a significant population. The close taxonomical relationship between olive tree and ash -both Oleaceae- has permitted to identify Fra e 1 (the Ole e 1-like allergen) in ash pollen and to detect the presence of protein homologues of Ole e 3 and Ole e 6. In the other hand, extensive areas of south Europe are suffering an increasing desertification. As a consequence of this, new botanical species are spontaneously growing in these areas or being used in greening ground programs: Chenopodium album and Salsola kali are some examples recently recognized as allergenic woods. The identification of the complete panel of allergens from the hypersensitizing sources might help to develop more accurate diagnosis, and efficient and safer therapy tools for Type-I allergic diseases.

The relationship of atopy, smoking, and sensitization to methyltetrahydrophthalic anhydride

We investigated the association of smoking, atopy and helper T (Th) cytokines with sensitization to methyltetrahydrophthalic anhydride (MTHPA) in occupationally exposed subjects. A population of 147 workers from two condenser plants using epoxy resin with MTHPA underwent a questionnaire survey and serologic investigation. Total and MTHPA-specific IgE levels were measured by the Pharmacia CAP system, and serum levels of interleukin (IL)-4, IL-13, and interferon-gamma (IFN-g) by enzyme immunoassay. The Pharmacia CAP-Phadiatop test, which detects serum IgE specific to most common aeroallergens, was also used. Ninety-six (65%) of the currently exposed workers had positive MTHPA-specific IgE. A significant difference was found in the frequency of positive specific IgE between atopic and non-atopic subjects (P<0.01), but not between smokers and non-smokers. As for smoking, the frequency of positive specific IgE was significantly (P<0.005) higher in smokers than that in non-smokers in non-atopic subjects. Multiple logistic regression analysis also confirmed significant contribution of atopy and smoking to the development of specific IgE (odds ration=3.2 and 10.5, respectively), suggesting that atopic subjects who became sensitized to P<0.01 may become sensitized to common aeroallergens. On the other hand, none of the Th cytokines contributed to the elevation of specific IgE levels. These results suggest that atopic subjects and non-atopic smokers are at increased rist of sensitization by P<0.01. However, to evaluate conclusively the effect of atopy on sensitization, further prospective studies are necessary.

Reference values of total serum IgE and their significance in the diagnosis of allergy in young European adults

Allergic sensitization mediated by immunoglobulin E (IgE) is the basis of allergic diseases, and elevated total IgE, in spite of some well-known limitations, is frequently included as a diagnostic criterion for allergic diseases. The reference value of total IgE (IgE-t) in the literature (1.5-144 kU/l) was established almost 2 decades ago. The aim of this study was to establish IgE-t reference values, establishing an updated cutoff value able to identify atopic subjects, defined as a positive CAP-radioallergosorbent test to at least one of a panel of common allergens, among young European adults. The study included 6,670 subjects from 10 Western European countries within the framework of the European Community Respiratory Health Survey II. IgE-t and specific IgE (IgE-s) were measured for the main inhalant allergens; IgE-s in class 0 for all allergens (66.2%) characterized non-atopy. The reference values were estimated by means of linear regression using a 50% random subsample of non-atopic subjects. Two non-atopic subsamples were examined so that one subsample could be used to establish reference IgE-t values, and these values were compared to those in the second non-atopic subsample to validate the findings. Sensitivity and specificity for atopy were assessed on the other 50% of non-atopic and on all atopic subjects. The 95th percentile of IgE-t reference values in non-smokers was 148 kU/l in women and 169 kU/l in men, while it was 194 and 220 kU/l in female and male smokers, respectively: serum IgE-t above the 95th percentile identifies <32% and above the 99th percentile <20% of atopic adults (low sensitivity), but a serum IgE-t below the 95th percentile identifies >90% and below the 99th percentile identifies >95% of non-atopic adults (good specificity). Due to the adequate specificity, IgE-t values exceeding the normal limits confirm a suspected atopic status; however, because of the low sensitivity, values below the cutoff seem not to exclude an atopic status with sufficient accuracy.

Prevalence and clinical relevance of specific immunoglobulin E to pollen caused by sting- induced specific immunoglobulin E to cross-reacting carbohydrate determinants in Hymenoptera venoms

BACKGROUND

Hymenoptera stings can induce specific IgE (sIgE) to carbohydrate determinants (CD) on venom glycoproteins that cross-react with CD in pollen. sIgE to such cross-reacting CD (CCD) are believed to have little or no biological activity and thus may cause misdiagnosis of pollen sensitization after a sting.

OBJECTIVE

To determine the prevalence of multiple false positive CAP results to pollen because of sting induced anti-CCD sIgE in Hymenoptera venom (HV) allergic patients and to investigate the association of such anti-CCD sIgE with features of 'atopy'.

METHODS

Skin prick tests (SPT) and CAP tests with grass, tree and weed pollen and with house dust mite (HDM) were carried out prospectively in 259 HV allergic patients and CAP tests with honeybee (HBV) and yellow jacket (YJV) venom were performed. Patients with negative pollen SPT associated with positive CAP tests to all three pollen groups were operationally defined as 'CCD positive'. We investigated in selected 'CCD positive' patients the presence of anti-CCD sIgE by CAP tests with bromelain and studied the identity of CD in HVs and pollen by mutual sIgE inhibition tests with CD from proteinase treated HBV (HBV-CD) and Lolium perenne (Lol-CD) extracts.

RESULTS

sIgE to all three pollen groups without positive SPT or history was found in 16% of 259 patients. The presence of anti-CCD sIgE was substantiated by positive CAP tests with bromelain in 14/14 and by inhibition of all pollen CAP tests with HBV-CD in 8/9 and with Lol-CD in 2/2 patients. Double venom (DV) positive CAP tests were present in 93% of 'CCD positive' patients and were in some associated with DV skin test positivity and allergy. The prevalence of 'CCD positivity' was significantly higher among HBV (23%) than among YJV (11%) allergic patients, but was also unexpectedly high among those with DV allergy (47%). 'CCD positive' patients were younger, had a higher total IgE and more sIgE to HDM than 'CCD negative' patients.

CONCLUSION

We have shown that the risk in HV allergic patients for misdiagnosis of multivalent pollen sensitization is 16%, and we have confirmed that sting induced anti-pollen sIgE are directed to similar CD in venoms and pollen. We found evidence that the recognition of CCD might be related to the 'atopic' trait. Importantly, a positive bromelain CAP test does not exclude clinical reactivity to both venoms in 'CCD positive' HV allergic patients.

Che a 1: Recombinant Expression, Purification and Correspondence to the Natural Form

BACKGROUND

Pollinosis to chenopods is one of the main causes of allergy in desertic regions and it is increasing in the South of Europe and Western USA. Che a 1 is a major allergen for chenopod-allergic subjects and belongs to the Ole-e-1-like family of proteins.

METHODS

Pichia pastoris yeast has been used as expression system to produce the recombinant form of Che a 1 (rChe a 1). The allergen was isolated using a gel permeation column and reverse-phase/high-performance liquid chromatography. Molecular characterization was performed using Edman degradation, mass spectrometry and concanavalin A staining. Sera from patients allergic to chenopod pollen, as well as polyclonal and monoclonal antibodies raised against Ole e 1, were used in immunoblotting, ELISA and inhibition assays for immunological characterization of rChe a 1.

RESULTS

The allergen was purified to homogeneity with a final yield of 15 mg/l of cell culture and showed a glycosylated character. N-terminal amino acid sequence of rChe a 1 and molecular mass were according to those of the protein isolated from chenopod pollen. The recombinant allergen maintained the IgG and IgE epitopes of the natural allergen deduced from the immunological assays.

CONCLUSIONS

Structural and in vitro immunological properties of rChe a 1 produced in P. pastoris were equivalent to those of the natural form of the allergen and, thus, it could be used in testing patients allergic to chenopods.

A relatively high prevalence and severity of asthma, allergic rhinitis and atopic eczema in schoolchildren in the Sultanate of Oman

OBJECTIVES

Although asthma, allergic rhinitis and eczema are among the most common chronic diseases in children worldwide, there is very limited information about the burden of these conditions in Oman. The aim of this study was to determine the prevalence and severity of symptoms of asthma, allergic rhinitis and eczema in Omani schoolchildren using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase I questionnaire.

METHODS

An Arabic version of the ISAAC Phase I questionnaire was completed by parents of 3893 children aged 6-7 years and self-completed by 3174 children aged 13-14 years, randomly selected from a nationwide sample of public schools.

RESULTS

The prevalence rates of reported diagnoses of asthma, allergic rhinitis and eczema were higher in older children (20.7%, 10.5% and 14.4% compared with 10.5%, 7.4% and 7.5%, respectively, in young children). In young children, 277 were current wheezers and of these 40.8% had sleep-disturbing wheeze at least once a week and 45.1% had speech-limiting wheeze during the past year. Similarly, 283 older children were current wheezers, and of these 30.0% had sleep-disturbing wheeze at least once a week and 37.5% had speech-limiting wheeze during the past year. Exercise-induced wheeze was higher in older children (19.2% vs 6.9%; P < 0.001). Allergic rhinitis and eczema were also associated with significant sleep disturbance and limitation of activity in both age groups.

CONCLUSION

Allergic conditions in Omani schoolchildren are common and associated with significant morbidity. Further research is required to identify the local risk factors for allergy to allow better understanding and management of these conditions.

Prevalence of asthma, allergic rhinitis, and eczema in 13- to 14-year-old children in Kuwait: an ISAAC study. International Study of Asthma and Allergies in Childhood

OBJECTIVES

To determine the prevalence of asthma and allergic diseases in 13 to 14 years old children in Kuwait.

DESIGN

Supervised self-administered written and video questionnaires of the international study of asthma and allergies in childhood (ISAAC).

SUBJECTS

Students at third and fourth years from 40 intermediate level schools chosen randomly from across Kuwait.

RESULTS

3,110 students were surveyed. The prevalence rates (95% CI) in the written questionnaire for wheeze ever, current wheeze (within the last 12 months), and physician diagnosis of asthma are 25.9% (24.5 to 27.4), 16.1% (15.8 to 17.4), and 16.8% (15.5 to 18.1) respectively. The prevalence rates (95% CI) for symptoms of allergic rhinitis (AR) ever, current symptoms of allergic rhinitis (AR), and diagnosis of AR are 43.9% (42.2 to 45.6), 30.7% (29.1 to 32.4) and 17.1% (14.8 to 18.4) respectively. The prevalence rates (95% CI) for itchy rash ever, current itchy rash, and diagnosis of eczema are 17.5% (16.2 to 18.8), 12.6% (11.4 to 13.8), and 11.3% (10.2 to 12.4) respectively. The prevalence of wheeze ever, wheeze during the last year, and physician diagnosis of asthma are higher in males compared with females, P < .01. In multiple logistic regression: male gender (OR 1.6, 95% CI, 1.3 to 2.0) and diagnosis of AR (OR 1.7, 95% CI, 1.4 to 2.2) were associated with the physician diagnosis of asthma even after controlling for symptoms of asthma.

CONCLUSION

This is the first study on the prevalence of allergic diseases in Kuwait and it shows that children in Kuwait have a moderate prevalence of asthma, AR, and eczema compared with other countries where the ISAAC study is done. The prevalence of asthma is higher in boys compared with girls.

Sensitization to aeroallergens among patients with allergic rhinitis in a desert environment

BACKGROUND

The causative allergens of allergic rhinitis in desert environments are uncertain.

OBJECTIVE

To determine the sensitizing aeroallergens in patients with allergic rhinitis in Kuwait, a desert country.

METHODS

A total of 706 patients aged 6 to 64 years (mean 34.3 years) with allergic rhinitis were studied. Sera from the patients were screened for specific IgE to 14 inhalant allergens by the CAP-RAST method.

RESULTS

Specific IgE to any allergen was detected in 86.3% of patients. The prevalence rates for allergen groups were: pollens (77.3%), house dust (62.3%), and molds (14.7%). The individual allergens with the highest positive rates were pollens of the weed Chenopodium (64.3%); Bermuda grass (55.0%), and Prosopis tree (50.3%). These plants were all imported and cultivated for the purpose of "greening" the desert. German cockroach (48.2%) and house dust mites (32.4% to 39.2%) were the most prevalent indoor sensitizers. With the exception of the molds, sensitization rates were higher for males than females. The youngest age group (6 to 17 years) had significantly higher sensitization rates than the older ones, particularly with respect to the molds (P < .01 to .001). Severe sensitization was more common with Alternaria than the other allergens and in general mold sensitization was more frequently associated with severe symptoms. Polysensitization was very common, with 81.8% of all sensitized patients positive to more than one allergen.

CONCLUSIONS

Pollens of the local horticultural plants are the main sensitizing allergens among patients with allergic rhinitis in this desert environment. The practices that "green" the desert seem to also encourage allergen sensitization.

Asthma in the desert: spectrum of the sensitizing aeroallergens

BACKGROUND

Bronchial asthma is common in Kuwait, a desert country, but the sensitizing allergens are uncertain. This study investigated the sensitizing allergens in Kuwaiti patients with extrinsic asthma.

METHODS

A total of 553 asthmatics (male:female ratio: 1.4; mean age: 31.7 years [range 3-76 years]) and 112 matched controls were studied. Sera from all patients/subjects were tested by the CAP-RAST method for specific IgE to 14 locally relevant inhalant allergens.

RESULTS

Specific IgE to at least one allergen was detected in 87.2% of the patients compared with 24.1% of controls. Among the confirmed extrinsic asthmatics, the sensitization rates for the allergen groups were as follows: pollens (87.1%), house dust (76.1%), and molds (30.3%). The three most prevalent sensitizing pollens were from Chenopodium (70.7%), Bermuda grass (62.9%), and Prosopis (62.7%), all of which are horticultural plants imported for the purpose of "greening" the desert. For all allergens, except the molds, the prevalence rate was higher in males than females, but age had only a weak effect. Severe asthma occurred significantly more frequently among mold-sensitized patients.

CONCLUSIONS

These results show that even in a desert environment, pollens and house-dust allergens may be important sensitizing allergens. They also illustrate how practices that "green" the desert can affect public health.

Allergy to date fruits: characterization of antigens and allergens of fruits of the date palm (Phoenix dactylifera L.)

BACKGROUND

Date-palm (Phoenix dactylifera L.) fruits are eaten daily by most inhabitants of the Middle East and the neighboring countries. Recent reports have indicated that dates are allergenic. This study aimed to investigate the antigenic and allergenic potential of date fruits.

METHODS

Date-fruit extracts from eight cultivars were evaluated in skin prick tests (SPT) in an atopic population, used to produce antisera, analyzed by SDS-PAGE, and fractionated by gel-filtration chromatography. Sera from SPT-positive individuals were evaluated by ELISA and RAST, and in anti-igE immunoblot experiments.

RESULTS

About 13% of patients were SPT-positive for at least two extracts. SDS-PAGE of whole extracts revealed 15-18 protein bands of 6.5->100 kDa, and Sephacryl S-200 fractions gave distinct peptide bands. RAST and anti-IgE ELISA gave a range of positive results, which could be abrogated when sera were preabsorbed with fruit extracts. IgE immunoblots of different extracts with pooled positive sera revealed different anti-IgE-binding immunoprints. All the positive sera from fruit-allergic and pollen-allergic individuals bound strongly to two anti-IgE reactive bands of 6.5 to 12-14 kDa and 28-33 kDa, respectively, and about 50% of sera bound to a 54-58-kDa band.

CONCLUSIONS

These results strongly indicate that 1) date-palm fruit is a potent allergen 2) sera from fruit-allergic as well as pollen-allergic patients recognize common fruit-specific epitopes 3) there is heterogeneity in patient responses to the different extracts.

Reference values of total serum IgE and their significance in the diagnosis of allergy among the young adult Kuwaiti population

BACKGROUND

The reference total serum immunoglobulin (IgE) values and the usefulness of total IgE values in the diagnosis of allergy have not been established for the Kuwaiti population. The literature reference values may not be applicable since such values often vary among ethnic nationalities.

OBJECTIVE

The aim of this study was to establish the reference IgE values for the young adult Kuwaiti population and to determine the usefulness of such values in the diagnosis of allergic diseases in the community.

METHODS

A total of 1057 randomly selected young adults were screened for atopy using the Pharmacia CAP-PhadiatopR method. Atopy was detected in 423 individuals (40.0%). Total serum IgE was then measured in 542 randomly selected Phadiatop-negative (non-atopic) cases in the age range 18-50 years (mean 28.9 years) and male:female ratio of 1.3.

RESULTS

Serum total IgE values in non-atopics covered a very wide range (< 2-1993 kU/L) with a geometric mean (GM) value of 43.7 kU/L. The reference range, calculated as the 95% confidence interval of the log IgE (95% CI) was 3.2-602.5 kU/L. The 90% CI was 11.7-162 kU/L. The GM was significantly higher for males than females, (53.7 vs. 35.5 kU/L, P < 0.001) and for smokers than non-smokers, (64.6 vs. 40.7 kU/L, P < 0.01), but was independent of age. Although the GM for the non-atopics (43.7 kU/L) was significantly lower than those of the asymptomatic atopics (213.8 kU/L) and allergic asthmatics (626.6 kU/L), the 95% CI for the three groups showed considerable overlap.

CONCLUSIONS

These results show that the normal total IgE values in the young adult Kuwaiti population are generally high and that the distribution of the values is so wide that the diagnostic value of total serum IgE in this community is likely to be very limited.