ELISA in Diagnosis of Respiratory Allergy

An enzyme-linked immunosorbent assay (ELISA), employing beta-galactosidase conjugated anti-IgE, was used for the determination of specific IgE antibodies to common inhalant allergens (Dermatophagoides pt. and f., Parietaria and four grass pollens) in serum samples from 82 adult patients with asthma and/or rhinitis. A total of 194 analysis were carried out and the results were compared with those of skin tests and RAST. The correlation coefficient (r) between ELISA and RAST results was high (r = 0.95); the correlation between skin tests and ELISA (r = 0.93) was greater than that between skin tests and RAST (r = 0.90). No significant differences were found among the allergens used. We conclude that the version of ELISA used develops an overall good correlation with skin tests and RAST and seems to provide a satisfactory alternative to RAST for allergy diagnosis.     

Food Sensitivity Reported by Patients with Asthma and Hay Fever

Among adult patients with bronchial asthma and/or allergic rhinitis und allergological investigation with skin test, nasal provocation test and RAST, 1129 answered a questionaire regarding food sensitivity (FS). 276 (24%) of the patients reported some kind of allergic symptoms on eating or handling various foods, of which hazel nut, apple and shell fish were the most often mined. Females reported FS most often than males, A correlation was found between birch pollen allergy and FS with nuts, apple, peach, cherry, pear, plum, carrot and new potato. The higher the degree of birch pollen allergy, according to skin test. RAST or provocation test, the higher the frequency of FS.
A correlation was found too between acetylsalicylic acid intolerance and FS with some foods, e.g. nuts, strawberry, almond, green pepper, hip, chocolate, egg, cabbage, milk and wine.
The connection between birch pollen allergy and FS is probably explained by the structural relationship between birth pollen allergen and some allergens of die foodstuffs, whereas the high incidence of FS in acetylsalicylic acid-intolerant patients is probably explained by additives in foods as well as salicylates or benzoates naturally occurring in some food.     

Allergy to Pollen from Different Deciduous Trees in Sweden

92 adult patients with springtime allergy were investigated with skin tests, provocation tests and the RAST. Allergen extracts from 12 different deciduous trees were used.
Positive reactions, often of high intensity, were most often found with birch, alder, bog-myrtle, beech and hazel allergens whereas oak, aspen, linden, elm, sallow, maple and poplar allergens more often gave negative or only weak positive test results. Cross sensitizations were found between botanically related as well as between less related species of the trees. Almost all patients with a clinically relevant tree pollen allergy had positive provocation tests with birch pollen. No patient had positive reactions to all the 12 allergens included in the study. 68% had positive provocation tests with the combination birch, alder and hazel.
It is concluded that for diagnostic screening purposes it is sufficient to use birch pollen allergen. If the majority of relevant tree pollens are to be included in a diagnostic or therapeutic programme in Western Sweden it should contain birch, alder, hazel, beech and bog-myrtle allergens.     

Cow milk allergy within the spectrum of atopic disorders

In order to examine the relationship between cow milk allergy (CMA) and atopic disorders in childhood, a consecutive group of 42 infants with IgE mediated CMA was followed for at least 2 years. The incidence of sensitization to common food and inhalant antigens and the development of eczema, asthma, and food allergies was examined for the cohort and compared between patients whose CMA remitted and those with persistent disease. In this cohort the prevalence of eczema was 57%, asthma 69%, egg allergy 67%, peanut allergy 55%, and 83% of infants demonstrated positive skin-prick tests to three or more allergens. At the end of the study CMA had remitted in 13 patients (median age 44 months) whereas in 29 patients it persisted (median age 44 months). Although there was no significant difference in the incidence of eczema or asthma during the study between these two patient groups, the incidence of allergy to egg and peanut butter was significantly greater for children with persistent CMA. Consistent with our hypothesis that children with persistent CMA have a more severe dysregulation of IgE synthesis than those whose disease remits, patients with persistent CMA had a significantly higher incidence of and level of skin sensitivity to inhalant and other dietary allergens. Sensitization to the inhalant allergens Dermatophagoides pteronyssinus, cat dander and rye grass was frequently seen in early infancy and increased during the study period. Thus, children with IgE mediated CMA frequently generate IgE responses to multiple dietary and inhalant allergens in infancy and early childhood and develop immediate hypersensitivity to other foods as well as clinical eczema, and asthma.     

Evaluation of a capsulated hydrophilic carrier polymer (the ImmunoCAP) for measurement of specific IgE antibodies

The Pharmacia CAP System is a new assay for serum specific IgE, utilising a solid phase capable of binding more antigen than conventional systems. The CAP System has been evaluated in 69 consecutive patients referred to one allergy clinic in relation to skin prick test (SPT), radioallergosorbent test (Phadebas RAST) and specific allergy diagnosis for five inhalant allergens, D.pteronyssinus, timothy grass pollen, cat epithelium/dander, Cladosporium and Alternaria. Good correlation was obtained between RAST and CAP for all allergens, e.g. r = 0.974 for D.pteronyssinus and r = 0.964 for grass pollen. When sensitivity and specificity were examined for both CAP and RAST versus SPT, CAP was usually found to be of greater sensitivity than RAST, and of similar or slightly lower specificity. SPT gave more positive reactions than either in vitro test, but CAP gave more positives than RAST. Twenty-two of 336 (6.6%) tests were CAP positive/RAST negative, whereas a negative CAP with a positive RAST occurred in only 2/336 (0.6%) tests. Of patients with any test (SPT or RAST or CAP) for specific IgE positive, up to 20-30% did not have clinical allergy, confirming the importance of the history in interpreting these tests. Our results suggest that, for the allergens tested, the Pharmacia CAP System is more sensitive than the RAST, identifying more positive tests and approximating more closely to the SPT. It offers the additional advantages of speed and efficiency.     

Diagnostic value of a glass fibre-based histamine analysis for allergy testing in children

The aim of this study was to compare the diagnostic value of common allergy tests with basophil histamine release in 124 children with symptoms of asthma. The patients were evaluated by case history, skin prick test, RAST-analysis, and basophil histamine release using a glass fibre-based histamine assay to 10 common inhalant allergens. The bronchial provocation test was used as a reference of "true" IgE-mediated asthma. To compare the various diagnostic parameters each absolute test value was classified into a scoring system. The concordance between the tests varied between 85-97%. In general, the best concordance was found between basophil histamine release and RAST. Sensitivity, specificity and predictive values were calculated on the basis of 104 bronchial provocation tests. It was found that histamine release was the best single analysis, followed by RAST and prick testing. The sensitivity of RAST and histamine release was very high (1.00) for pollen and house dust mites. Histamine release showed a predictive value between 0.91 and 1.00 for pollen and house dust mites, thus indicating the possibility of omitting the bronchial provocation test. In the dander group histamine release gave the best sensitivity (0.91), however at the expense of specificity (0.64), whereas RAST and skin prick test gave a specificity of 1.00. In the mould group histamine release also showed the best diagnostic value. The combination of skin testing with histamine release or RAST was of no additional diagnostic help. It is concluded that the glass fibre-based histamine analysis, which makes routine histamine release testing possible, is a reliable diagnostic test in children.     

Relationship of Allergen-Specific IgE Antibodies, Skin Prick Tests and Allergic Disorders in Unselected Adolescents

The relationship between serum levels of allergen-specific IgE (RAST) and skin prick test reactivity and allergic disorders was evaluated in 137 subjects randomly selected from an adolescent population. All subjects were prick tested with six common allergens, interviewed and physically examined. In addition, serum was collected for RAST analysis with three to six allergens. At least one positive RAST result (score 1-4) was observed in 40% and at least two positive RASTs in 22% of the subjects. Boys experienced more RAST reactions and generally with higher scores than girls. For instance, 26% of boys but only 11% of girls were RAST positive to timothy grass pollen. The correlation between prick test and RAST results was better with pollens than with house dust and animal epithelia. When the test results were discordant, the skin test was usually positive and RAST negative. Many of the small skin reaction (weal diameter 3-4 mm) were accompanied by a negative RAST. Respiratory allergy was closely connected with both positive skin test and RAST reactivity, while atopic dermatitis was less related. In 17% of the adolescents positive skin tests and in 14% positive RASTs occurred in the absence of any allergic symptoms. We conclude that a positive RAST score 3-4 to inhaled allergens is a strong indicator of clinical allergy but low scores 1-2 are frequently found in healthy young people.     

Investigation of the Involvement of Echium plantagineum (Paterson's Curse) in Seasonal Allergy

The possible allergenicity of an insect pollinated weed, Echium plantagineum , was investigated in a rural area of Australia. Sixty-one subjects with respiratory allergy were studied. Positive skin test reactions to defatted ammonium bicarbonate extract of pollen were found in over 60% of subjects, and positive RAST tests in a similar number. The question of cross-reactivity between weed pollens is discussed. The pollen of E. plantagineum was shown to reach the atmosphere in significant amounts about 1 month before the peak grass pollinating period. Evidence that the pollen of E. plantagineum becomes airborne and elicits an IgE response suggests that further attention should be directed to weed pollens as potential allergens.     

Long-Term Changes in Inhalant Allergy in Asthmatic Children

In a representative cohort of 55 asthmatic schoolchildren the progress of the allergy per se was followed up prospectively for 8 years. Judged by clinical data, skin prick tests and RAST, a large majority of the children retained their allergies to pollen and animal danders. These allergens were predominant, whereas allergy to mites and moulds was less frequent. Serum IgE levels showed a strong tendency to remain high. Positive RAST and skin prick tests were also found in a substantial number of children with normal serum IgE concentrations.     

Comparison of results of skin prick tests (with fresh foods and commercial food extracts) and RAST in 100 patients with oral allergy syndrome

One hundred adult patients with a history of oral allergy syndrome (OAS) after ingestion of fruits and vegetables, 77 patients with hay fever and 13 with skin prick tests and RAST positive to pollens but without seasonal symptoms, and 32 normal nonallergic control subjects, had Phadebas RAST and skin prick tests with commercial extracts (CSPT) and with fresh foods (FFSPT) to assess the reliability of these three tests. Sensitivity was better with FFSPT for carrot, celery, cherry, apple, tomato, orange, and peach; better with CSPT for peanut, pea, and walnut; and better with RAST for hazelnut. Specificity, negative predictive value, and positive predictive value of the three tests were determined for apple, carrot, hazelnut, orange, pea, peanut, and tomato. Specificity in the patient groups ranged between 40% (pea) and 100% (apple) for CSPT, between 61% (peanut) and 87% (carrot) for RAST, and between 42% (carrot) and 93% (peanut) for FFSPT. However, all tests were negative in the control group. Thus, false positive results may result from cross-reactivity with pollen allergens. The diagnostic accuracy of these tests in the population with OAS proved comparable for peanut, carrot, hazelnut, and pea. FFSPT proved more sensitive than CSPT or RAST in confirming a history of OAS to certain alimentary allergens, such as apple, orange, tomato, carrot, cherry, celery, and peach.     

Allergy to feathers

Skin prick test reactivity to commercial and self-made feather-allergen extracts was examined in 269 consecutive adult patients with suspected allergic cutaneous or respiratory symptoms who had been referred to a university clinic. Some 177 subjects reacted to any inhalant allergen. Twentyfour (9% of the whole group and 14% of those positive to any inhalant allergen) reacted to commercial feather extracts from ALK (Hørsholm. Denmark), and 51 to any of the seven feather extracts used. Feather-mix RAST (Pharmacia, Sweden) was positive in three cases only. Skin prick test or CAP-RAST or both to house-dust mite were positive in 16 of those 24 subjects positive to the commercial feather extracts, but in only 23 of the 150 other atopic subjects (P<0.001). A nasal challenge with a feather extract was made in 20 cases, always with negative result. In immunospot studies, concomitant allergy to feather-allergen extracts and house-dust mite could be demonstrated. Mite allergens in feather extracts were verified in RASTinhibition studies. A clinically significant feather allergy was found in one patient only. The results suggest that true feather allergy is very rare, and most of the positive reactions seen in skin prick tests to feather extracts are probably caused by mite allergens present in feathers.     

Allergy to foods in patients monosensitized to Artemisia pollen

It is known that patients with pollinosis may display clinical characteristics caused by allergy to certain fruits and vegetables, but subjects allergic to Artemisia seem to show particularly peculiar characteristics. The clinical features of 84 patients with rhinitis, asthma, urticaria, and/or anaphylaxis whose inhalant allergy was exclusively to Artemisia vulgaris were studied and compared with a control group of 50 patients monosensitized to grass pollen. The mean age for the beginning of symptoms was 30.2 years, and this was higher than in the control group ( P <0.05). We found the main incidence to be in women (70.2%). Some 42.3% had family history of atopia, lower than in the control group ( P <0.05), while the prevalence of asthma and urticaria was significantly higher ( P <0.05). Food hypersensitivity was reported by 23 patients (27.3%) allergic to Artemisia. The foods responsible (with respective numbers of cases) were honey (14), sunflower seeds (11), camomile (four), pistachio (three), hazelnut (two), lettuce (two), pollen (two), beer (two), almond (one), peanut (one), other nuts (one), carrot (one), and apple (one). None of the patients monosensitized to grass had food allergy. CAP inhibition experiments were carried out on a single patient. Results showed the existence of common antigenic epitopes in pistachio and Artemisia pollen for this patient. We concluded that mugwort hay fever can be associated with the Compositae family of foods, but that it is not normally associated with other foods.     

Sensitization to oilseed rape is not due to cross-reactivity with grass pollen

BACKGROUND: Oilseed rape is an important crop grown in the UK which can cause specific immunological sensitization with clinical symptoms in a relatively small number of the general population. Individuals with immunoglobulin (Ig) E-mediated allergy to oilseed rape have also been found to be sensitized to other pollen allergens, most frequently being grass pollen. Cross-reactivity between common grass and oilseed rape would have important implications, especially as their flowering period coincides. OBJECTIVE: We have investigated whether the cosensitization found in individuals sensitized to both oilseed rape and grass pollen is due to cross-reactivity. METHODS: Cross-reactivity between oilseed rape and grass pollen was determined using RAST, RAST inhibition, Western blotting and inhibition studies with Western blotting. RESULTS: Competitive RAST inhibition studies between pollen of oilseed rape and grass failed to show any cross-reactivity between the pollen types. Self-inhibition with oilseed rape resulted in 90% inhibition, whereas there was less than 10% inhibition with grass pollen. Western blotting revealed allergens of similar molecular weight in both oilseed rape and grass pollen. Despite allergens of similar molecular weights being present in both pollen types, inhibition immunoblot studies confirmed that the allergens in the two allergens were immunologically distinct. CONCLUSION: The allergens of oilseed rape and grass pollen, although similar in molecular weights, are immunologically distinct and there is no evidence of cross-reactivity between them. Individuals allergic to grass pollen will not necessarily develop a specific nasal or airway response to inhaled oilseed rape pollens.     

The prevalence of latex allergy in children seen in a university hospital allergy clinic

Natural rubber latex allergy is responsible for a wide spectrum of clinical symptoms, ranging from rhinoconjunctivitis to severe anaphylaxis, in both adults and children. An association between allergy to latex and allergy to various fruits has been reported. This study investigated the prevalence and clinical significance of latex sensitization in children seen in a university hospital allergy clinic. A total of 453 consecutive children were screened in a 7-month period. A detailed clinical history with particular attention to the past surgical history and the eventual presence of latex- or food-induced allergic symptoms was obtained. Skin prick tests (SPT) for the more important inhalant allergens and foods were performed on all children. In patients with positive latex SPT, latex challenge and additional SPT for some fresh foods (avocado, pineapple, apricot, grape, banana, pear, apple, orange, almond, and chestnut) were also performed. RAST for the same food antigens, as well as patch test with latex and a standard battery of contact allergens, was also done. Of 326 atopic children, 10 (3%) presented positive skin test to latex, but only five (1.5%) also had a positive clinical history to latex exposure. Latex challenge was positive in 3/9 positive-latex-SPT children. None of the nonatopic children had positive skin test to latex or symptoms to latex exposure. A history of previous surgery was found in 5/10 positive-latex-SPT children, in 63/316 negative-latex-SPT atopic children (P<0.05), and in 23/127 nonatopic children. RAST to latex was positive in 5/10 positive-latex-SPT children. Associated fruit-specific IgE (SPT and/or RAST) were found in all latex-symptomatic children and in 2/5 latex-asymptomatic children. Apple, kiwi, and chestnut were the most common SPT-positive foods. Only one patient with clinical allergy to latex and positive skin tests to fruits had a history of clinical symptoms after ingestion of kiwi and orange. The natural history of the positive-latex-SPT children without clinical reactions to latex exposure and the clinical significance of the association of latex and fruit sensitivity require further studies.     

Allergy to Birch Pollen and Apple, and Gross-Reactivity of the Allergens Studied with the RAST

Apple-pulp allergens arc unstable, but fresh material can be used for skin testing. In this study stable allergens, probably of a protein nature, were extracted from apple seed and used in radioallergosorbent tests (RAST). Apple-seed allergens were shown by RAST inhibition to cross-react with birch pollen allergen(s). Cross-reactivity may explain the frequent co-occurrence of birch pollen and apple allergy. Approximately 50% of patients in a group with immediate hypersensitivity to birch pollen were also sensitive to apple as judged by a history of symptoms, skin tests with apple-pulp and apple-seed preparations, and apple-seed RAST.     

The Role of Cow Milk Allergy in Increasing the Severity of Atopic Dermatitis

Previous studies have shown that up to 33% of children with atopic dermatitis have experienced food hypersensitivity and among different kinds of food allergens Cow Milk (CM) has almost always been one of the most common food allergens in children. The aim of this study is to evaluate the cow milk allergy (CMA) as an increasing factor of severity of atopic dermatitis. One hundred and nineteen children (between 1.5 months and 12 years of age) with atopic dermatitis in the sense of Hanifin and Rajka's criteria entered this study and the severity of atopic dermatitis was identified via the SCORAD index. In order to make the diagnosis of cow milk allergy, a careful history, and a familial history of allergy was taken and the results of skin prick test (SPT) with CM and 4 other food allergen extracts, Radioallergosorbent test (RAST) with CM allergens and a food challenge test with cow milk (fresh or dried) were used. Also a total serum IgE determination and an eosinophil count (with a stool exam) were accomplished. The clinical manifestations of atopic dermatitis in patients was started from their first day of life up to 10 years of age. The family history in 83% of the patients was positive. Positive skin prick test and RAST with CM allergens were positive in 37.9% and 29.3% of cases respectively and the response to challenge test with cow milk was positive in 35 out of 40 patients and in total 44.5% had CMA according to a positive history of cow milk allergy and a positive outcome of the IgE tests (SPT and/or RAST) or a positive challenge test with CM allergens. The results showed that the most common food allergens in patients with atopic dermatitis are certainly cow milk allergens (44.5%) whereas other food allergens are tomato (29.41%), egg (28.57%), nuts (9.24%) and wheat (3.36%) according to the skin prick test. The mean total serum IgE was 307.11 ± 6.56 IU/ml (range = 6–5000) in children with CMA and 81.04 ± 5.97 IU/ml (range = 1–5000) in children without CMA while the mean eosinophil count was 569.52 ± 3.02 count/ml (range = 67–8500) and 314.22 ± 2.94 count/ml (range = 5–5000) respectively. The mean severity of atopic dermatitis according to the SCORAD index was 60.76 in children with CMA and 44.29 in children without CMA. The severity of atopic dermatitis in patients with CMA was significantly higher than patients without CMA (p < 0.0001). Also the mean total serum IgE and mean eosionophil counts in children with CMA were significantly higher than in children without CMA (P < 0.01 and p < 0.0001, respectively). It shows the important role of CM allergen proteins in the induction and in increasing the severity of AD in children.     

Diagnosis of reaginic allergy with house dust, animal dander and pollen allergens in adult patients. I. A comparison between RAST, skin tests and provocation tests.

RAST analyses were performed with house dust, animal dander and eleven pollen allergens in 410 adult patients with asthma and/or rhinitis and the findings were compared with skin test and provocation test results. The overall correlation between 1,316 provocation tests and RAST was 78% and the correlation between 1,778 skin tests and RAST was 66%. The relationships between RAST and in vivo tests differed considerably from allergen to allergen. No significant differences were found between various age groups. According to the in vivo tests the RAST showed more often positive results in patients with pronounced allergy than in patients with low-grade allergy. Higher RAST classes were most often combined with positive in vivo tests. It is concluded that in cases with RAST classes 2-4, a reasonably well-established allergy diagnosis can be reached without the inclusion of additional in vivo tests. In other cases, however, application of further diagnostic methods is required.     

Comparative evaluation of RAST and MAST-CLA for six allergens for the diagnosis of inhalant allergic disease in 232 patients

The aim of this study was to compare a recent multiple allergosorbent chemiluminescent assay (MAST-CLA) with the RAST for the diagnosis of inhalant allergic disease in 232 patients with rhinitis and/or bronchial asthma. As judged by concordance of clinical history, skin prick tests to a range of six allergens common to our geographic area, and by nasal provocation tests, 70 patients were non-allergic and 162 allergic: 70 to grasses, 46 to mites, four to mugwort, eight to pellitory, and 34 were sensitive to several allergens. In our patient sample that, among other things, comprises subjects with fairly rare monoallergies, MAST-CLA testing gave results which closely corresponded to positive RAST for the allergens studied, and demonstrated a close correlation with the diagnosis of inhalant-specific allergy. Our results showed that, for overall allergens, MAST-CLA was lightly less sensitive and more specific than RAST (the two in vitro tests gave an identical overall efficiency).     

Clinical significance of specific IgE determination on nasal secretion

The clinical use of RAST on the nasal secretions was investigated in seventeen atopic patients, with asthma or rhinitis, who had shown at a first diagnostic screening, some difficulties in the identification of the responsible allergen(s). The results of the skin tests, of the RAST on the serum and on the nasal secretions and of the specific provocation test (bronchial or nasal) were compared. In some cases the basophil degranulation test was performed. The results of the RAST on the nasal secretions were in perfect agreement with the provocation test. The skin tests and the RAST on the serum showed many discrepancies, particularly for Dermatophagoides, epidermal derivatives of cat and dog and moulds, and less frequently for Graminaceae and other pollens. It is concluded that RAST analysis on nasal secretions is useful in clinical diagnosis of allergy especially for Dermatophagoides, epidermal derivatives and moulds. Most false positive results were observed with the RAST on serum; in fifteen cases it was positive, while all the other tests, basophil degranulation test included, were negative. The data suggest that IgE may have a low affinity for basophil receptors.     

Development and comparative evaluation of a multiple-antigen RAST as a screening test for inhalant allergy

We have developed a modified in vitro test for IgE antibodies, the multi-RAST, to detect antibodies of different allergen specificities simultaneously in a single tube. The multi-RAST is as sensitive for detecting low concentrations of individual IgE antibodies as the discrete RAST. We also evaluated the multi-RAST as a screening test for respiratory allergy to inhalant allergens in children by comparing the results of the multi-RAST performed by use of a mixture of SRP, TGP, and DF allergen-immunosorbents with the results of skin tests, discrete RAST tests for the same allergens, serum total IgE concentrations, and nasal smears for eosinophils in 100 children referred for allergic-disease evaluation. The results of the multi-RAST were more sensitive, specific, and efficient than the results of tests for serum IgE concentration and nasal eosinophils in establishing the diagnosis of inhalant allergy; the multi-RAST was the only diagnostic test that yielded results that were significantly associated with the clinician's impression of allergy. We conclude that the multi-RAST is a useful and cost-effective screening test for inhalant allergy in children.