Clinical evaluation of a new enzymo-assay for allergen-specific IgE

A new assay for the determination of specific IgE in serum, using a monoclonal anti-IgE (Stallerzym), was evaluated. Compared with the results of skin prick tests, the Stallerzym was found to be 93% specific and 73% sensitive. In sera from patients selected to be either clearly allergic or not allergic (as defined by the concordant results of case history, skin prick test, and provocation test), Stallerzym proved to be as accurate and reliable as the Phadezym IgE RAST currently available.     

Specific immunoglobulin E antibodies in tear secretions of patients with vernal conjunctivitis

Twenty-two patients with vernal conjunctivitis (VC) were studied by radioallergosorbent test (RAST) for specific IgE antibodies to the inhalant pollen allergens in tear secretions. Specific IgE antibodies were detected in the tear secretions of 12 (54.5%) patients with VC. Six patients had a positive tear RAST, but the corresponding serum RAST and immediate skin test reactivity were negative. The specific tear IgE antibodies appeared to correlate with the seasonal prevalence of the pollen in the environment and the period of maximal symptomatology. Six patients had both positive serum and tear RAST determinations. A double ratio formula with transferrin as a marker for the leakage of plasma proteins into tear secretions and the “specific activity” ratios of IgE antibody to total IgE between the tear secretions and the serum indicated that almost all (79% to 99%) of the tear IgE antibodies were locally produced. IgE antibodies were also detected in the tears of four of 10 patients with allergic conjunctivitis (AC) and of three with allergic rhinitis (AR). However, the “specific activity” ratio in the patients with AC and AR with measurable tear IgE suggested that the IgE antibodies were derived from the leakage of serum proteins into the tear secretions. These findings suggest that the pathogenesis of VC may be IgE mediated in some patients and lends support to the concept that specific IgE antibodies can be produced locally by the target organ, i.e., conjunctival tissues.     

In vitro screening for inhalant allergy with multi SX 1 RAST® (Phadiatop®)

A new in vitro screening test for inhalant allergy (Phadiatop, Pharmacia Uppsala, Sweden) was evaluated for its effectiveness in identifying allergic patients. The test is based on the radio-allergo-sorbent-test (RAST). Specific IgE antibodies to different inhalant allergens are detected simultaneously. Serum samples from 300 patients and controls were run with Phadiatop. 96% of 150 patients with proved allergic disease were correctly identified by Phadiatop. 92% of 150 individuals without clinically relevant allergic hypersensitivity were found correctly to be negative. Allergic disease was proved or excluded by case history, skin prick test, RAST and, in some cases, additionally by provocation challenge.     

Discrepancies between the skin test and IgE antibody assays: study of histamine release, complement activation in vitro, and occurrence of allergen-specific IgG

Intracutaneous skin tests (STs) and RAST with the common allergens, grass pollen, house dust mite, and cat dander, were performed on 660 adult patients. In 117 patients (18%), we found 140 discordances (7%) in a total number of 1980 ST and RAST combinations. In agreement with studies in the literature, greater than 80% of the discordances consisted of positive skin reactions without detectable allergen-specific IgE antibodies in serum. The percentages of discordant results were similar for the three allergens. Reproducibility of both the RAST and the ST was evaluated in the discordant group. Repetition of the routine RAST procedure elicited results similar to those in the first test in 81% (105/130). A second ST elicited identical results in 89% (47/53). In addition to the routine IgE antibody assay, sera of patients with a positive ST but without detectable IgE antibodies were tested in two other RAST systems: (1) a RAST with allergen extracts from the same production batch as the ST reagents, and (2) the Pharmacia RAST. In spite of having a clearly positive ST, sera from 68 (80%) of 85 patients remained completely negative in all three RAST systems. Histamine release (HR) in vitro from washed leukocytes was studied in 35 patients with a reproducible positive ST and negative RAST results with serum. Interpretation of this test was possible in 28 patients. In 82% (23/28) of these patients, clearly detectable HR was found with the relevant allergen extract. A role of IgE in the skin reactions and HR tests was confirmed by positive RAST results with IgE that was affinity purified from serum of seven of these patients. Allergen-specific IgG4 antibodies are unlikely to be implicated, since no antibodies against grass pollen and house dust mite were detectable in sera of these patients. Only 18% of the patients with an unexplained skin reaction with cat dander have detectable IgG4 antibodies, but these antibodies were found in a similar frequency in a nonallergic, ST negative control group. Low total IgG responses precluded false negative RAST results caused by competition of IgG antibodies with IgE antibodies. There were no significant differences in the degree of complement activation in vitro by house-dust extracts between healthy control subjects, nonallergic patients, and patients with unexplained skin reactivity. It is concluded that a high proportion of the positive skin reactions with common inhalant allergens, which are not accompanied by a positive RAST, are probably caused by IgE antibodies that are not detectable in serum with any of the RAST procedures.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

Specific IgE antibodies in nasal secretion from patients with allergic rhinitis and with negative or weakly positive RAST on the serum

Nasal secretions from eighteen patients with allergic rhinitis with a positive case history, intradermal test and nasal provocation test, but with negative or only weakly positive RAST (radioallergosorbent test) on the serum against a total of thirty-five allergens, were studied. In the RAST an immunosorbent-purified anti-IgE with D?2 specificity was used, which raised the detection limit. Nasal secretion was collected by washing the nasal mucosa with 0.9% and 18% NaCl solution respectively, and the latter secretion was also lyophilized and concentrated. In ten cases RAST was slightly positive on the nasal secretion, and in three of the concentrated secretions the RAST value was higher than on the serum. In none of the serum or nasal secretion samples was RAST positive according to the cut off value for a positive result defined by the reference system used in Phadebas RAST®. From these results it is concluded that RAST analyses of nasal secretion from patients with allergic rhinitis is of no appreciable value in routine clinical allergological diagnosis. However, the increased sensitivity of RAST obtained with isotope-labelled anti-D?2 may be useful in the serological diagnosis of patients with low grade allergy having low levels of IgE antibodies in serum.     

Evaluation of MAST-26, newly developed system for the detection of IgE antibodies]

MAST-26 is a new allergy testing system which allows simultaneous determination of allergen-specific IgE antibody levels for 26 allergens using 200 microliters of patient serum. To evaluate the effectiveness of MAST-26 for the detection of allergen-specific IgE antibody, a total of 100 serum samples were collected from allergic patients at five facilities, and allergen-specific IgE antibody was measured by MAST-26. 14% of them were positive to > or = 10 allergens. If the patients had severe allergic symptoms, they were likely to show positive to many allergens. A good correlation was found between the results obtained by MAST-26 with those measured by CAP RAST and by intradermal skin test. It was concluded that MAST-26 is an effective screening method for the detection of allergen-specific IgE.     

Efficacy of a single diagnostic test for sensitization to common inhalant allergens.

BACKGROUND: UniCAP Phadiatop is a single laboratory test designed to determine the presence or absence of specific IgE to a variety of common inhalants. Its purpose is to aid in the differentiation of patients with symptoms attributable to allergic disease from other common causes. METHODS: Consecutive children and adolescent patients (n = 145) at two centers were examined by having their history and physical examination performed by two board certified allergists. Their conclusions along with skin prick tests and specific IgE measurements regarding seven common inhalants (mite, oak, ragweed, grass, dog, cat, Alternaria) were compared with UniCAP Phadiatop test results. This was done using concordance of all test results. Attempts to resolve test discrepancies, when found, included specific RAST inhibitions, total IgE values, and physicians' judgment after testing. RESULTS: All patients with resolved diagnoses (143 of 145, 103 positive and 40 negative) were identified correctly by the UniCAP Phadiatop test. Skin test results and specific IgE measurements correlated well, but neither correlated well with the history by itself, suggesting a minimal false-positive component of the history of 23%. UniCAP Phadiatop results demonstrated a quantitative relationship between the patient's score and the amount of IgE specific to these individual allergens. CONCLUSIONS: The UniCAP Phadiatop test was shown to be highly sensitive and specific in differentiating individuals who are sensitized to common inhalants from those who are not. This test is recommended to all physicians as an aid in diagnostic and referral decisions for patients suspected of having an inhalant allergic diathesis.     

Chironomidae as a cause of IgE-mediated histamine release in patients with asthma

The present study was undertaken to assess the importance of Chironomidae as an allergen causing bronchial asthma in Japan, and to evaluate histamine release as an allergy test in chironomid-midge allergic patients. Extracts of Chironomidae (T. akamusi and C. Yoshimatsui) caused the release of histamine in six out of 13 allergic patients with positive skin tests. In contrast, histamine release induced by these allergens was not observed in leukocytes from two asthmatic patients and five control subjects without IgE antibody as evidenced by negative skin tests and RAST. There was a significant correlation between maximal histamine release and IgE antibody levels. Furthermore, a significant inverse relationship between the concentration of allergen causing 25% histamine release (HR25) and IgE antibody levels was observed. The correlation coefficients, however, between histamine release and RAST were not high, and there were discrepancies between the two tests in some cases. These results suggest that Chironomidae induce histamine release from leukocytes via IgE-mediated mechanism but histamine release cannot be replaced by RAST and also suggest that chironomid midge is one of the important allergens in Japan.     

Incidence of IgG short-term sensitizing antibodies in an allergic population.

Heat-stable, immunoglobulin G, short-term sensitizing antibodies (IgG S-T S) were sought in serum from 149 allergic patients who had strongly positive immediate skin tests to inhalant allergens. The sera were tested by passive cutaneous anaphylaxis (PCA) in monkeys. No IgG S-T S antibodies were demonstrated in 169 tests with a variety of allergens. Antibody with the characteristics of IgE was demonstrated in 47% of monkey PCA tests and, in an additional 34% of sera. IgE antibody to the same allergen was demonstrated by radioallergosorbent testing (RAST).     

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.     

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.     

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.     

Inhibition Experiments with Solid Phase Mite or Epithelia in House Dust Hypersensitivity

The present study was undertaken to verify that mites are not the only allergens in house dust extracts and that other allergens such as cat epithelia can also be responsible for house dust hypersensitivities detected both by house dust skin tests and house dust RAST studies. In order to determine whether mite or epithelia fixed on a solid phase could remove not only the IgE antibodies reactive with the homologous allergens, but also the IgE antibodies reactive with house dust allergens, the authors have absorbed 10 sera of house dust allergic patients with solid phase mite or epithelia. The absorption procedure removed a large part of the IgE antibodies reactive with specific immunosorbent (Dermatophagoides pteronyssinus or cat epithelia) and in the same way the IgE antibodies reactive with house dust immunosorbent. The percentage of RAST inhibition varied from 65% to 92% for Dermatophagoides pteronyssinus and from 65% to 94% for house dust in patients allergic to house dust and mite; the percentage of RAST inhibition varied from 67% to 92% for cat epithelia and from 73% to 90% for house dust in patients allergic to house dust and cat epithelia. This is in accordance with the hypothesis that house dust is not an allergen per se, but rather a complex mosaic of several allergens including mite, animal epithelia, etc.     

Comparison of a new type of skin test (Phazet) with existing skin test methods and the radioallergosorbent test (RAST)

A new skin test method (Phazet) for diagnosis of immediate-type allergic disease was tested in 232 patients attending the Guy's Hospital Allergy Clinic, and compared with conventional skin test methods, using Bencard and Pharmalgen allergen solutions, and with serum IgE antibody tests (RAST). Six allergens (cat, dust mite, Cladosporium, grass pollen birch pollen and plantain pollen) were used, as well as histamine and a negative control. Phazet proved easy to use and was popular with inexperienced operators (medical and dental students). For the majority of allergens there was reasonably good agreement with the different tests, but overall Phazet and RAST produced fewer positive results than the other skin tests methods. In particular, the frequency of positive histamine tests was lower with Phazet (82%) than with Bencard or Pharmalgen (99%), but this discrepancy was lower in the second part of the study when the minimum time for the insertion of the needle (1 sec) was more scrupulously observed. Phazet offers a convenient and practical alternative to conventional 'wet' skin test methods.     

Specific IgE to reindeer epithelium in Finnish reindeer herders

Reindeer herding is a major source of living for more than 4200 inhabitants in northern Finland. To determine the prevalence of allergic symptoms among reindeer herders clinical examinations and skin prick tests (SPT) with nine inhalant allergens were performed in 211 randomly selected men from 21 to 69 (mean 45) years. Specific IgE antibodies to reindeer epithelium (RE) and total serum IgE were evaluated in 99 herders, five persons who handled reindeer leather indoors, 21 atopic patients with cow allergy and another 20 subjects with specific IgE to other inhalant allergens. Positive SPT to RE was detected in one and specific IgE by using enzyme allergosorbent test (EAST) (greater than or equal to 0.8 PRU/ml) in seven herders. Specific IgE to RE was also demonstrated in one control. Using RAST inhibition a patient with cow allergy did not show cross-reactivity between cow and RE while another patient did. Thus, RE should be included in the allergy test panel when hypersensitivity to RE is suspected.     

Relationship between antigen-specific IgE antibody (RAST) and total serum IgE levels.

Although the total serum IgE level is generally higher in atopic than in non-atopic individuals, high total serum IgE levels and atopic diseases are not invariably associated. In 42 atopic patients with the total serum IgE levels less than 100 U/ml, 27% of RAST against 14 allergens were positive whereas in 45 atopic patients with the total serum IgE levels greater than 500 U/ml, 57% of RAST against 14 allergens were positive. The mean RAST values against four grass antigens expressed as a percentage of antigen-disc bound radioactivities were significantly lower in the group with the lower total serum IgE levels. Low or normal total serum IgE levels are likely to be found in atopic patients who are allergic to a relatively few grass antigens.     

Serum IgE and atopy in drug-sensitive patients

One of the most interesting aspects of the pathogenesis of the allergic and pseudo-allergic reactions to drugs is the one concerning the possible roles of genetic factors, in general, and the relationship with atopy, in particular. We decided to study the correlation between the serum level of total IgE, the personal and familial history of atopy, and the allergologic tests (skin test, PRIST, RAST, etc) for one or more drugs taken by 465 patients with personal history of allergic reactions. From the data, we observed that the average amount of total IgE lies within the norm, 125.4 KU/L (+/- 209.2), without any significant difference between the allergic (132 KU/L) and the pseudo-allergic (121.8 KU/L) patients. The IgE levels tend to be higher in that part of the tested population which presented a circumstantial atopic status (11.8%) and they are not influenced by an allergic or pseudo-allergic reaction to drugs. According to these results, the relationship between drug hypersensitivity and atopy needs further investigation.     

Increased specificity of diagnostic tests with recombinant major bee venom allergen phospholipase A2

Background In diagnosis of type I allergy recombinant allergens have potential advantages over conventional allergenic extracts, both regarding specificity and reproducibility. Objectives We therefore decided to study honey bee venom (BV) and its major allergen phospholipase A2 (PLA) in native and recombinant form for diagnosis of bee sting allergy. Method We investigated 85 patients with a history of a recent systemic allergic bee sting reaction and positive intracutaneous skin test to BV, and 21 controls with no history of allergic bee sting reaction and negative skin test to BV. Intracutaneous skin tests and determination of specific IgE by ImmunoCAP^R to BV, native PLA (nPLA) and recomhinant PLA (rPLA) were done in all patients and controls. Results In skin testing 84 (99%) of the 85 patients reacted to nPLA and 81 (95%) to rPLA, while none of the 21 controls was positive with nPLA or rPLA. Specific serum IgE to BV could be detected in 82 of the patients (96%), to nPLA in 73 (86%) and to rPLA in 66 (78%). Four (19%) of the controls had a positive CAP to BV, one (4.8%) to nPLA and none to rPLA. Analysis of discordant results in CAP showed, that most patients with specific IgE to BV, but not to nPLA and rPLA, had positive skin tests to both PLA preparations and low levels of BV specific IgE. Patients with specific IgE to nPLA but not to rPLA were usually sensitized to minor allergens of BV which contaminated the commercial nPLA. Conclusions PLA is the major allergen in BV. While diagnostic tests with BV are more sensitive, the specificity of tests with PLA, especially rPLA is clearly increased as compared with BV.     

Influence of hyposensitization with Dermatophagoides pteronyssinus extract on clinical score, total and specific IgE levels, and skin test in asthmatic patients

To evaluate the effects of immunotherapy on clinical response, on IgE serum level, on radioallergosorbent test (RAST), and on skin tests, a prospective study was performed by a follow-up of 73 asthmatic patients allergic for house dust during hyposensitization with Dermatophagoides pteronyssinus extract. No relationship could be found between the evolution of clinical score, skin tests and RAST, but 91% of the patients with a decreasing IgE serum level had satisfactory clinical results. Serial determinations of serum IgE levels during hyposensitization showed two patterns of evolution with a favourable prognostic value: a continuously decreasing serum IgE or a primary increase followed by a late decrease.