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.     

The radioallergosorbent test (RAST) in the diagnosis of reaginic allergy

Provocation tests, skin tests, and RAST were performed in 156 asthmatic children, using eleven different allergens (moulds, animal danders, and pollens). A total of 305 positive and 676 negative provocation tests were performed. For positive provocations there was an overall agreement with RAST in 61% of the instances, for negative bronchial tests in 94%. The agreement was found to be allergen dependent. By combining RAST and skin tests, it was possible to arrive at a conclusive allergy diagnosis in a higher number of instances than if either skin testing or RAST was used alone, but in a considerable number of instances provocation tests were found to be necessary to secure the allergy diagnosis. The results obtained with RAST in this study were less favourable than those of other studies, probably because of the use of lower quality allergosorbent material.     

Comparison of skin tests and RAST in the diagnosis of atopic hypersensitivity.

Prick, intracutaneous tests and the radioallergosorbent test (RAST) were performed with 12 common allergens in 50 consecutive patients who required skin testing during an allergy investigation. Results of prick test and RAST showed agreement in 82.7% of tests but positive prick tests were much commoner than positive RAST tests. When intracutaneous tests were required to obtain a positive skin test, agreement between skin test and RAST fell to 66.5%.     

RAST in the diagnosis of hypersensitivity to dog and cat allergens A comparison of different extract preparations with clinical history, skin test and provocation tests

A comparison was made of clinical signs and provocation tests with the RAST for allergy to dog in eight and cat in twenty patients. Twenty-two had high IgE levels and all gave positive reactions to provocation tests. A commercially available dog epithelium extract gave more positive RASTs than five other dog allergen preparations, and there were no positive reactions to dog serum. The RAST was negative in patients with a low degree of sensitivity. All twenty patients allergic to cat gave positive intracutaneous test reactions and in the RAST the cat epithelial allergen showed 90% agreement with the in vivo findings.     

Allergy to the coffee plant

Occupational respiratory allergy to green coffee beans in coffee roastery workers is well established. I now report on a 50-year-old female atopic patient sensitized to the coffee plant used for indoor decoration. The symptoms were rhinitis and conjunctivitis on exposure to the plant. Investigation showed a positive skin prick test, RAST, and rhinoconjunctival provocation test to coffee leaf allergen extract. However, the commercially available RAST disk for green coffee beans seems to be appropriate for diagnosing allergy to the potted coffee plant.     

Correlation of the specific IgE in serum and nasal secretions with clinical symptoms in atopies

In an unselected population of 133 young adults studied by prick testing to common allergens three groups were identified: eleven subjects with positive skin test responses and clinical symptoms of allergy; ten subjects only with positive skin tests and the remainder with negative skin tests. All subjects with positive skin tests (with and without symptoms) were studied by RAST on the serum and nasal secretions. Specific and non-specific bronchial provocation tests (BPT) were also carried out. The serum RAST was positive in all subjects with positive skin tests, and there was good correlation between high levels of circulating specific IgE and the presence of clinical symptoms. The RAST of nasal secretions was negative in most symptom-free subjects and as a diagnostic lest it was slightly better than the serum RAST. BPTs with extracts of the relevant allergens caused bronchospasm in every subject with a positive nasal secretion RAST. Only two subjects out of fifteen with a positive response were clinical asthmatics. Our results cast doubt on the clinical relevance of the BPT as it is usually conducted.     

Allergenic activity of fractions of cocksfoot (Dactylis glomerata) pollen

A cocksfoot (Dactylis glomerata) pollen extract has been fractionated by isoelectric focusing in polyacrylamide gel, the separated components extracted from the gel and assayed by three methods: prick tests in human skin, RAST and PCA tests in monkey skin. Prick testing in human skin showed that subjects responded differently to the separated components, indicating the presence of more than one antigenic determinant, and a prolile of antibody activity against each fraction could be constructed. In general, good agreement was observed between RAST profiles and skin test profiles, although some patients who gave positive skin tests lacked circulating IgE and consequently did not give a RAST profile or a monkey PCA. These studies emphasize the current difficulty in attempting to isolate a single pure allergen from cocksfoot which can be used either diagnostically for the detection of pollen allergy, or for the standardization of diagnostic extracts.     

Wheat allergy: diagnostic accuracy of skin prick and patch tests and specific IgE

BACKGROUND: Food allergy makes an important contribution to the pathogenesis of atopic eczema in infants. However, clinical data on cereal allergy are scanty. The objective was to study the relevance of patch testing, skin prick tests, and the concentration of wheat-specific IgE antibodies (CAP RAST) in correlation with oral wheat challenge in infants with suspected wheat allergy. In particular, we aimed to determine whether the patch test could increase the diagnostic accuracy in detecting wheat allergy. METHODS: The study material comprised 39 infants under the age of 2 years. Of these patients, 36 were suffering from atopic eczema and three had only gastrointestinal symptoms. The patients were subjected to a double-blind, placebo-controlled or open wheat challenge. Wheat-specific IgE was measured by CAP RAST, and skin prick and patch tests were performed. RESULTS: Of the total 39 wheat challenges, 22 (56%) were positive. Of the positive reactions, five involved immediate-type skin reactions over a period of 2 h from the commencement of the challenge. In 17 patients, delayed-onset reactions of eczematous or gastrointestinal type appeared. Of the infants with challenge-proven wheat allergy, 20% showed elevated IgE concentrations to wheat, 23% had a positive skin prick test, and 86% had a positive patch test for wheat. The specificities of CAP RAST, skin prick tests, and patch tests were 0.93, 1.00, and 0.35, respectively. CONCLUSIONS: Our study demonstrated that patch testing with cereals will significantly increase the probability of early detection of cereal allergy in infants with atopic eczema and is helpful in the planning of successful elimination diets before challenge. The specificity of the patch test was lower than that of other tests. Therefore, confirmation of the diagnosis with the elimination-challenge test is essential in patients with positive patch test results.     

Diagnosis of reaginic allergy with house dust, animal dander and pollen allergens in adult patients. V. A comparison between the enzyme-linked immunosorbent assay (ELISA), provocation tests, skin tests and RAST.

An enzyme-linked immunosorbent assay (ELISA) employing allergen adsorbed onto the internal surface of a plastic tube, and alkaline phosphatase conjugated anti-IgE was used for the determination of specific IgE antibodies to various inhalant allergens in serum samples from 255 individuals with asthma and/or allergic rhinitis. A total of 541 analyses were carried out and the results were compared with those of provocation tests, skin tests and the RAST. It was found that negative ELISA values with high probability indicated nonallergy and very high ELISA values (class greater than or equal to 5) indicated allergy. However, the proportion of positive ELISA values which did not correspond to clinical allergy was high, as were the number of intermediate, inconclusive values (class 1-2). Although significant correlations between the ELISA values and provocation test, skin test or the RAST were obtained with some allergens, it was concluded that our version of the ELISA has not advantages over currently used methods for allergy diagnosis.     

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.     

Skin and serologic testing in the diagnosis of latex allergy

Background: Latex hypersensitivity is associated with occupational allergy contact urticaria, rhinitis, asthma, and anaphylaxis. However, standardized sensitive and specific latex extract for skin prick or serologic testing is not available in the United States.Methods: We investigated the reliability of two latex extracts in 118 consecutive skin tests in patients with spina bifida, health care workers, and other patients with symptoms of latex allergy, and 10 control subjects.Results: Forty-two of 86 patients with spina bifida, 11 of 15 health care workers with symptoms of latex allergy, 6 of 7 patients with symptoms of latex allergy, and 0 of 10 control subjects had demonstrable immediate wheal and flare responses to latex prick testing. In addition, 95 patients and 10 control subjects were tested concurrently for latex-specific IgE by ELISA. Of 55 patients with positive skin prick test results, 48 were reactive as determined by ELISA for IgE-specific latex antibody (sensitivity = 87%). Latex ELISA titers were significantly higher in patients with positive skin prick test results with a history of anaphylaxis to latex and in individuals without symptoms of latex allergy who had positive skin prick test results when compared with patients with negative skin prick test results. During the skin test procedure, nine patients had adverse reactions, including anaphylactic reactions in four.Conclusions: Skin prick and serum testing are reliable methods of diagnosing latex allergy. Serologic evaluation may be more desirable until allergen standardization is available.     

Egg-white sensitivity and atopic eczema

Thirty-four children with atopic eczema were studied for egg-white sensitivity. Clinical manifestations, skin reactivity to egg-white antigen, IgE, by radioimmunoassay (RIA), and specific reaginic IgE antibodies to egg white by the radioallergosorbent test (RAST) were evaluated. Patients were divided into two groups on the basis of clinical sensitivity to egg-white antigen. Of 13 eczematous patients in Group I with known clinical egg sensitivity, 2 had RAST levels between 0 and 24 per cent, 6 between 25 and 100 per cent, and 5 had levels greater than 100 per cent. In this group, 5 had positive prick skin tests to egg white. Of 21 eczematous patients in Group II with no demonstrated clinical egg sensitivity, 17 had RAST levels of 0 to 24 per cent, 3 had RAST levels between 25 and 100 per cent, and one had an RAST level greater than 100 per cent. In this group, 3 had positive prick tests to egg white. The egg-white RAST showed a significant correlation with clinical egg sensitivity (p = 0.0005) and with a prick skin test of the same antigen (p = 0.036) but not with total serum IgE levels. However, no correlation was found between clinical egg sensitivity and egg-white prick skin test.     

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.     

Widespread immunoglobulin E-mediated hypersensitivity in the Sudan to the “green nimitti” midge,Cladotanytarsus lewisi (diptera: Chironomidae): I. Diagnosis by radioallergosorbent test

A radioallergosorbent test (RAST) has been developed for the diagnosis of hypersensitivity to “green nimitti” chironomid midges of the species Cladotanytarsus lewisi. There was a high percentage binding of ¹²⁵I-anti-IgE to the allergen particle complex by serum from subjects who were clinically hypersensitive, and the RAST was inhibited following incubations of allergic sera with an extract of the allergen. In 104 hypersensitive subjects (i.e., those with a positive skin test or clinical history of bronchial asthma, with or without rhinitis) and 21 controls, the RAST appeared to be specific and of diagnostic value: (1) The percentage binding was appreciably higher in 38 symptomatic individuals (group I) with strongly positive skin tests as compared with 36 patients with moderate skin reactivity (group II). (2) Seven symptomatic subjects with negative skin tests (group III) had a positive (>6% binding) green nimitti RAST. (3) Positive RASTs were demonstrable in 16 and of 17 patients with positive skin tests in whom the history was equivocal (group IV). (4) Six asymptomatic individuals with positive skin tests (group V) had low RAST values. (5) Six asymptomatic Sudanese controls with negative skin tests gave similar values to those of the group V subjects. (6) All of the sera from 15 nonatopic United Kingdom controls gave less than 6% binding of ¹²⁵I-anti-IgE. There was no statistical correlation between the concentrations of total IgE and the green nimitti RAST values. These results suggest that the RAST may be useful diagnostic test in green nimitti hypersensitivity and may also be of value in studies on the epidemiology and in the monitoring of treatment of this important and widespread allergy problem in the Sudan.     

Skin and radioallergosorbent tests in patients with sensitivity to bee and wasp venom

Intradermal (ID) and prick tests with bee or wasp venom (Pharmalgen) have been performed on 102 subjects with a history of adverse reactions to stings and forty-six control subjects giving no such history. Venom was diluted 100, 10 and 1 μg/ml for prick testing and 10^-2, 10^-2, 10^-3 and 10^-4%mUg/ml for ID injections. In forty-six control subjects all were tested with the highest concentration of prick testing solution (100 μg/ml), eight (17%) had positive reactions, a similar reaction rate to that reported in control subjects using 10^-1μg/ml ID. In our 102 test subjects skin tests were therefore regarded as positive only if the reaction was elicited by 10^-2μg/ml or less by prick test of 10^-2μg/ml or less ID. In general the results with skin prick tests and ID tests were comparable when the prick solution was 1000 times the concentration of that used for ID testing. ID tests were positive in thirteen with negative skin prick, seven of whom had detectable antibodies when tested by RAST. Conversely four with a positive skin prick test (two of whom were RAST positive) were considered negative on ID testing. As judged either by RAST or skin tests it appeared that sensitivity diminished with the time interval from the last sting (P< 0-001).     

Relationship between the results of bronchial, nasal and conjunctival provocation tests in patients with asthma

Skin tests and bronchial, nasal and conjunctival provocation tests with pollen and animal dander allergens were performed in thirty patients with atopic asthma. In vivo test results were compared only when the same batch of allergen had been used. A nasal reaction was mostly elicited at a lower concentration of allergen than was needed to elicit a bronchial reaction (P < 0·01). Positive nasal reactions were often obtained when the corresponding bronchial tests were negative. The conjunctiva reacted to lower concentrations than the bronchi in a third of the instances of testing, with most of these being tests with mugwort allergen (P < 0·05). A positive skin test in cases with a negative bronchial challenge test was often accompanied by a positive nasal test and in some cases by a positive conjunctival test. It is concluded that nasal or conjunctival provocation tests do not replace bronchial challenge tests. In an asthmatic patient who gives no reaction to bronchial challenge with a particular allergen, a positive skin test may reflect a nasal allergy.     

Basophil histamine release in the diagnosis of house dust mite and dander allergy of asthmatic children

The aim of the study is to compare the glass fibre-based basophil histamine release test with skin test (Phazet), RAST (Phadebas) and bronchial provocation test in children with allergic asthma. The study comprised 68 selected children with a case history of extrinsic allergic asthma to danders (cat and dog) and house-dust mite. Skin prick test, RAST, and histamine release were performed in all children and the bronchial provocation test was used as a reference of "true allergic asthma". A total of 81 allergen bronchial challenges were performed and 44 children experienced 49 positive provocations. In 2.9% (2/68) of the children histamine release could not be performed due to technical difficulties (low histamine release with anti-IgE). Concordances in the range 76-87% were observed with no significant difference between the tests. The highest concordance (87%) was found between histamine release and bronchial provocation test followed by skin prick test vs bronchial provocation (84%) and RAST vs bronchial provocation (80%). The sensitivity and specificity were calculated for each test. All tests showed sensitivities in the range 90-94% and no significant difference between them was observed. The specificity of histamine release, skin prick test, and RAST was 0.78, 0.69, and 0.63, respectively. The specificity of histamine release was better than RAST demonstrated by 95% confidence intervals. In conclusion, it was found that the histamine release test is a convenient diagnostic method and the study indicates a diagnostic value comparable to the common diagnostic methods in clinical allergy.     

Diagnosis of food allergy by the radioallergosorbent test

The radioallergosorbent test (RAST) was positive in 52.5% of 200 sera representing 200 food hypersensitivities from 108 patients with a history of definite immediate-type reactions to foods. Corresponding prick test was performed for 170 of the sera. The latter test was positive in 70%, the RAST was positive in 52%, and either prick test or RAST was positive in 74%. It is concluded that the RAST is positive less frequently than the prick test in the diagnosis of immediate-type food allergy in clinically sensitive patients, but that the performance of both tests increases slightly the possibility of confirming the diagnosis. However, the RAST is useful for further evaluating positive prick tests with foods that do not correlate with clinical hypersensitivity.     

IgE-mediated inhalant allergy against human corticotropin-releasing hormone

A 25-year-old female developed IgE-mediated sensitization against human recombinant corticotropin-releasing hormone (CRH) with symptoms of allergic rhinoconjunctivitis and bronchial asthma. The occupational allergy was proved by positive skin prick test, bronchial provocation, dose-dependent histamine release, RAST measurements with CRH allergen (RAST class 3) and RAST inhibition. Using the immunoblot technique, a single allergen band with a molecular weight of less than 14.4 kD in the range between the isoelectric point 5.2 and 5.7 was detected for the CRH extract. Since no endocrinological and behavioral disorders were found, increased CRH-specific IgE was not able to influence the regulatory control of this neuropeptide. After 18 months of avoiding the occupational CRH exposure allergen-specific histamine release and RAST were negative.     

Comparison of immunologic tests in the diagnosis of occupational asthma and rhinitis

In this study, three immunologic tests, skin prick test, RAST, and basophil histamine-release test (BHRT), were compared by provocation in the diagnosis of occupational asthma and rhinitis. Twenty-three positive bronchial or nasal challenges were performed on 16 patients (six farmers, six bakery workers, and four food industry workers) and asthma or rhinitis was diagnosed as caused by cereal flour or grain, cow epithelium, storage mites, garlic, or soy dust. A control group consisted of 12 patients, of whom four (two bakery workers, one food industry worker, and one farmer) were challenge-negative, and the rest suffered from pollen allergy and seasonal rhinitis and were not challenged. The sensitivity and specificity of the prick test, RAST, BHRT, and a panel of them were as follows: 74 and 89%, 57 and 86%, 78 and 93%, and 91 and 71%, respectively. The overall concordance among these three type I allergy tests or between immunologic tests and challenge was relatively good.