Detection of allergy to nuts by the radioallergosorbent test.

The diagnosis of food allergy is often difficult to make by conventional means. Histories are frequently ambiguous, and skin testing is of dubious reliability because of the number of false-positive and false-negative reactions. We have evaluated the radioallergosorbent test (RAST) for the in vitro measurement of the specific IgE antibodies to nuts, including Brazil nut, almond, walnut, pecan, cashew, and the legume, peanut. Serums were obtained from 18 patients with a history of nut allergy and IgE level and specific IgE antibodies were measured. Thirteen of the 18 patients had significantly elevated IgE antibody (greater than twice control) to one or more of the allergens. Prausnitz-Küstner tests on selected serums in general corroborated the results of the in vitro studies. Five patients had RAST elevations to 2 or more nuts. As a group RAST-positive patients had elevated mean serum IgE levels and more severe clinical symptoms (p less than 0.01). The specificity and cross-reactivity of IgE antibodies to different nut antigens was investigated by RAST inhibition with serums from 5 patients having high levels of IgE antibody. In 4 patients no cross-reactivity between Brazil nut and peanut was found. In contrast, several nut extracts inhibited the reaction of pecan allergen with IgE antibodies. These results indicate that specific IgE antibodies can be measured by RAST in patients with nut allergy and the cross-reactivity of nut antigens can be investigated. RAST would appear to be most useful in confirming the diagnosis of nut hypersensitivity in children or in highly allergic patients in whom skin testing poses a risk of anaphylaxis.     

Allergy to pistachio: crossre activity between pistachio nut and other Anacardiaceae

Background Anaphylaxis against Anucardiuccae nuts is uncommon and the allergens involved still poorly characterized. For this reason two patients with allergy towards pistachio nut (a member of the Anacardiaceae family) have been studied. Objective Identification of immunoallergens present in pistachio nut and analysis of crossreactive antigens in other members of the same plant family, specifically cashew and mango. Methads Presence of specific IgE for pistachio and cashew nut and for mango seed and pulp was determined by skin tests and radioallergosorbent assay (RAST). The allergenic profile of pistachio and cashew was analysed by sodium dodeeyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting. Crossreactivity between pistachio and the other Anacardiaceae was studied by RAST inhibition. Results Skin tests were positive for pistachio and cashew in the two children and for mango seed in one. RAST was positive for pistachio and cashew in both patients. On immunoblotting, serum from both patients recognized several pistachio and cashewallergens with a molecular weight ranging from <14.2–70kDa. RAST inhibition demonstrated common antigenic determinants between pistachio and cashew nut. Crossreactivity was also found between pistachio nut and mango seed but not with mango pulp. Conclusion Pistachio nut contains several protein allergens able to trigger type I hyperscnsitivity reactions. These allergens can be found also in cashew nut and mango seed but not in mango pulp.     

Double-blind food challenge in the diagnosis of food sensitivity in the adult

This study is an attempt to determine the role of double-blind food challenge (DBFC) in suspected food sensitivity in the adult as compared wih established tests of food allergy, including the skin test, RAST, and leukocyte histamine release (LHR) to specific food antigens. Twenty-two subjects (ages 18 to 67) with histories of reactions to foods were challenged with freeze-dried food or placebo in opaque dye-free capsules, in increasing doses over a 90 min span to a total of 13 to 15 gm. This was repeated twice at weekly intervals by similar DBFC. DBFC was preceded by skin testing and venapuncture for RAST and LHR studies. Patients were kept under observation for 2 hr, after which each was asked to maintain a detailed diary of related symptoms and food ingested over the following week. Of 46 DBFCs, 13 (21%) were positive. The correlation with positive skin tests and positive DBFC was 4/13 (30%). The correlation with positive LHR and positive DBFC was lower at 2/13 (15%), and 1/13 (7.6%) with RAST. We concluded that DBFC is an effective test of adult food sensitivity compared with tests usually performed and should be used when the diagnosis is in doubt.     

The irritable bowel syndrome and food hypersensitivity

Ten patients with irritable bowel syndrome were evaluated for food hypersensitivity with skin testing (IgE) and IgG serum antibodies (RAST panel) to common food antigens. Patients also underwent an open elimination diet for 2 weeks followed by a 48-hour challenge of each food that was considered to be suspicious from patients diary, positive skin prick test, and/or positive IgG antibodies. Six patients had positive skin scratch test results and only one patient had RAST IgG food antibodies greater than 3,000 cpm which is a marked increase above normal. None of the patients however had an exacerbation of their irritable bowel symptoms with a food challenge. We conclude therefore that positive skin testing and IgG serum antibodies are not reliable indicators of food hypersensitivity in irritable bowel syndrome and that food hypersensitivity does not seem to play a role in the symptoms related to the irritable bowel syndrome.     

Diagnosis of allergy in different age groups of children: use of mixed allergen RAST discs, Phadiatop and Paediatric Mix

Childhood asthma often begins in children under 3 years of age. Allergy contributes to the severity and persistence of childhood asthma so we examined the application of mixed allergen RAST discs (Paediatric Mix, a mixture of food antigens and Phadiatop, a mixture of inhalants) to the diagnosis of allergy. One hundred and nine children with a median age of 3 years, 71.6% of whom had asthma, were first assessed by one allergist who recorded their atopic status as positive, negative or questionable, on clinical grounds. Serum from each of these patients was used to determine a total IgE and 13 RAST assays. A laboratory definition of atopy was defined as a serum IgE > 1 standard deviation from normal, plus one or more positive RAST assays. The laboratory results influenced the assessment of atopy in 41% of cases. The use of just two mixed allergen discs (Paediatric Mix and Phadiatop) correctly assigned the presence or absence of atopy with a sensitivity of 98% and specificity of 98%, compared with the full laboratory evaluation. Very young infants were often just positive to food allergens but the Phadiatop disc could be used to suggest the onset of immunological sensitivity to inhalant antigens. Thus the application of mixed allergen RAST discs facilitated the diagnosis of atopy in young children.     

Simple allergen skin test device Multi skit (tentative name)

We have developed a device tentatively named Multi Skit (Mu), a simple allergen test device, in order to conduct the skin test safely, accurately and conveniently. The utility of this device was evaluated by determining how the results obtained by the intradermal test (In) and Mu were correlated with those obtained by IgE RAST (RA) in 65 AD patients. RA values concerning nine antigens were compared to results obtained by the In and Mu in terms of the positive and negative response coincidence rates, overall coincidence rates, and false-positive and false-negative response rates. The correlation between RA data obtained from the literature and the results of the scratch test (Sc) was also evaluated. The results of In and RAST values showed no correlation regardless of the food antigen used. Mu and RAST values showed correlation with respect to all 4 food antigens except soy-bean, resulting in overall coincidence rates of 66.2 to 87.7%, which were higher than those concerning the Sc. With respect to false-positive responses to environmental antigens, the rate obtained by Mu was higher than that by the Sc, but it was lower than that by the In. However, Mu was the most excellent test with respect to the other indices, i.e., positive and negative response coincidence rates, overall coincidence rates (73.9-89.2%) and false-negative responses. The mechanism of Mu makers it possible to minimize variations from one investigator to another, and the major drawback of all other skin tests. Mu is a safe and convenient screening skin test device which provides accurate and specific test results.     

Comparison of results of skin tests, RAST, and double-blind, placebo-controlled food challenges in children with atopic dermatitis

Forty children with atopic dermatitis were evaluated for clinical evidence of hypersensitivity to foods by double-blind, placebo-controlled food challenges. Twenty-four children (60%) experienced 33 positive challenges, manifested by cutaneous symptoms in 31 (94%), gastrointestinal symptoms in 14 (42%), nasal symptoms in nine (27%), and respiratory in six (18%). Results of prick skin tests (STs) and RASTs to eight food antigens frequently eliciting hypersensitivity reactions were compared with those from food challenges to determine the diagnostic accuracy in children with atopic dermatitis. Defining a positive ST as a wheal 3 mm larger than the negative control wheal and a positive RAST as a Phadebas RAST score of 3 or 4, the sensitivity, specificity, and predictive accuracies of these tests were found to be comparable except in the case of wheat antigen where the ST was clearly superior to the RAST. Accepting a RAST score of 2 or more as a positive slightly improved sensitivity in some cases but dramatically decreased specificity. Combining results of STs and RASTs did not improve significantly the diagnostic accuracy over results of the tests used individually. These studies demonstrate no advantage of RAST alone or in combination with prick skin testing over prick skin testing alone in the evaluation of food hypersensitivity in children with atopic dermatitis. Furthermore, skin testing should be considered a good test for excluding immediate food hypersensitivity but only a suggestive positive indicator of hypersensitivity due to the high rate of clinically insignificant positive STs.     

Specific IgE antibodies in atopic eczema

Radioallergosorbent tests (RAST'S) with 35 antigens and total serum IgE levels were performed on sera from 25 patients with atopic eczema, ranging from mild to very severe, who had been evaluated clinically and, when possible, skin-tested to inhalant allergens. IgE levels varied from 95 to 112,000 I.U., with a geometric mean of 2,200 I.U. Individual patients' sera gave an average of 8.4 positive RAST's to 14 inhalant allergens with a range of from 1 to 14 positive tests. The correlation of RAST with skin tests averaged 55 per cent with no difference observed with either the scratch or the prick methods. The degree of correlation was not related to severity of eczema. In eczema patients the great majority of noncorrelating tests were RAST positive and skin-test negative, unlike the noncorrelating tests found in children with asthma and allergic rhinitis, where there are more positive skin tests with negative RAST. The 25 sera were tested by RAST with 18 food antigens and the various sera gave from 1 to 18 positive tests, with an average of 9.7. IgE antibodies reacting with at least one of the DPT antigens were found in 10 of the 25 sera. Sera from 4 of the patients studied contained IgE antibodies that combined with all 35 antigens studied. Control RAST's with these sera were negative. This study shows that much of the elevation of serum IgE observed in atopic eczema represents specific IgE antibodies that can combine with common antigens with relatively high affinity.     

Sensitivity to tomato and peanut allergens in children monosensitized to grass pollen

Possible associations between allergy to grass pollen and positive skin tests to food allergens were studied in 102 children monosensitized (as to inhalant allergens) to grass pollen, and in 117 children monosensitized (as to inhalant allergens) to Dermatophagoides. Thirty-two foods were tested by an epicutaneous method. Positive skin tests to food allergens were more frequent in children with allergy to grass pollen (59.8%) than in children with allergy to Dermatophagoides (9.4%). A considerably high frequency of positive reactions to tomato (39.2%), peanut (22,5%), green pea (13.7%), and wheat (11.7%) was observed in children with allergy to grass pollen. Positive skin tests to peanut closely correlated with positive RAST results and nasal provocation tests, whereas in children with skin test positivity to tomato a close correlation with nasal provocation tests but a 45% correlation with a positive RAST result were observed. RAST inhibition experiments were carried out, and the results may suggest the presence of cross-reacting IgE to grass pollen, tomato, and peanut antigens. Clinical implications of these findings are discussed in the light of histories of food hypersensitivity, urticaria-angioedema, and atopic dermatitis in children with allergy to grass pollen.     

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.     

Highly atopic children: formation of IgE antibody to food protein, especially peanut

Highly atopic infants often form IgE antibodies toward multiple food protein in the first 2 years of life. They begin producing IgE antibody to inhalant allergens between the first and second year of life. We hypothesized that highly atopic children would be at significant risk of sensitization to peanut. We defined high atopy as serum IgE greater than or equal to 10 times 1 SD from normal plus multiple positive RASTs. In this study we have characterized the immunologic status of 141 patients by measuring total serum IgE and specific IgE to several allergens, including peanut. These data demonstrated that, independent of clinical history, a positive RAST to peanut was more common in the highly atopic category compared to the low atopy category. Significantly more patients who were highly atopic and had a positive peanut RAST had a positive RAST for egg or milk compared to low atopic patients. More significantly, 33 of the patients had never knowingly received peanut, yet 21 (63.6%) had a positive RAST for peanut, whereas seven (21.2%) had a peanut antibody in the highest RAST category. All these seven patients were considered highly atopic according to the definition above, and three were younger than 2 years of age. These results suggest that highly atopic infants are at special risk for sensitization to peanut, even when they have never received peanut, and that characterization of immunologic sensitization to milk, egg, and peanut will identify the highly atopic infant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potentiation of IgE production to common environmental allergens by storage house dust mite Dermatophagoides farinae

Total scrum IgE and IgE antibodies against ten common antigens, including Dermatophagoides farinae (D.f.), moth, ragweed, orchard grass, cryptomeria, alternaria, aspergillus, dog dander, cat dander and tetanus toxoid, were determined using the PRIST and the Sepharose-RAST, respectively, in 100 clinically non-allergic Japanese subjects and interrelations of IgE responses to these antigens were investigated. We obtained following results. (1) The number of positive RAST antigens, to which the subjects responded, increased in parallel to their total serum IgE levels. (2) Among ten antigens, D.f. and moth antigens contributed a great deal to the elevation of total serum IgE level as compared with other antigens. (3) When the relationship between IgE response to D.f. and similar responses to the other nine antigens was investigated, positive RAST responses to various antigens occurred selectively in the subjects with positive RAST for D.f., and the number of positive RAST antigens to which the subjects responded increased depending upon their D.f. specific RAST levels. (4) Such an association was not found between IgE response to moth and the other nine antigens. These findings suggest that non-specific activation of IgE-producing B cells occurs as a result of continuing stimulation by D.f.     

The oral Prausnitz-Küstner reaction in food allergies

The oral Prausnitz-Küstner (P-K) reaction was examined in 41 children suspected of IgE-mediated food allergy. The recipients were served by their mothers in this study. A positive reaction was observed in 9 children when used hen's egg, cow's milk, chicken, buckwheat, red-bean, salmon or common-dolphin. Among them, seven have had an anaphylactic skin reaction (systemic urticaria and/or angioedema) to the foods. The other two were babies who were fed only by the breast milk. Therefore, the oral P-K test may be useful for the diagnosis and the prediction of food-anaphylaxis. The sera that had the radioallergosorbent test (RAST) scores of 3 or greater were negative in the oral P-K reaction in 26 out of 36 tests, and the sera that showed the positive oral P-K reaction to buckwheat or chicken were zero in the RAST scores. These results suggest that a soluble substance (e.g., histamine-releasing factor) in addition to the IgE antibody might be involved in the oral P-K reaction, and that the RAST technique does not always detect the IgE antibody that recognizes the food antigens degenerated during the absorption in vivo.     

In vitro stability and immunoreactivity of the native and recombinant plant food 2S albumins Ber e 1 and SFA-8

BACKGROUND: The ability of an intact protein to reach the circulatory system may be a prerequisite to allergenicity and many allergens, particularly those from plant foods, have been found to be consistently more resistant to digestion by pepsin than other proteins. OBJECTIVE: This study assessed the pepsinolytic stability of native 2S albumins from Brazil nut and sunflower seed and their recombinant versions produced in Pichia pastoris. The physicochemical stability of native and recombinant Brazil nut 2S albumins and recombinant sunflower seed 2S albumin was also assessed. The immunoreactivity of native Brazil nut 2S albumin and recombinant 2S albumins was compared using serum from patients allergic to Brazil nuts and animals immunized with native 2S albumins. METHODS: Digestibility was measured in simulated gastric fluid followed by SDS-PAGE. Circular dichroism spectra were used to analyse unfolding, as proteins were denatured by temperature, pH and guanidinium chloride. Immunoreactivity was assessed by immunoblot, RAST and ELISA. RESULTS : Brazil nut 2S albumin was significantly more resistant to proteolytic digestion than other Brazil nut proteins. It was also resistant to thermally and chemically induced denaturation. Equally high resistance to proteolytic digestion was observed with sunflower seed 2S albumin. The recombinant albumins mirrored their native counterparts in stability and immunoreactivity. CONCLUSION: The important food allergen Brazil nut 2S albumin is as stable to digestion as is sunflower seed 2S albumin, whose allergenicity has yet to be determined. The 2S albumins and their recombinant counterparts could not be easily denatured by physicochemical treatments. The results suggest that 2S albumin is the only Brazil nut protein to reach the gut immune system intact. The production of properly folded recombinant proteins will facilitate mechanistic studies as well as diagnostic testing and antigen-based therapies.     

Allergy to mice. I. Identification of two major mouse allergens (Ag 1 and Ag 3) and investigation of their possible origin

An extract of dust from the outlet filters of a mouse isolator was used as a basis for determining the source of inhalant allergens for subjects sensitive to this species. The antigenic components, identified by crossed immunoelectrophoresis (XIE), were compared to those found in extracts of other mouse-derived source materials, i.e. urine, fur, dander and saliva. Of the eight dust components, one (Ag 1) was identified as antigenically identical to the major urinary pre-albumin whilst the others were detected in fur, and to a lesser extent dander and saliva. None of the dust antigens was detected as a component of food or bedding.
Crossed radio-immunoelectrophoresis (XRIE), performed using sera from a group of fifteen mouse-allergic subjects (positive by RAST to mouse extracts), identified seven of the dust antigens as IgE-binding components. Antigens 1 and 3 were reactive with all the sera tested and have, therefore, been termed the'major'allergens. Varied responses were obtained to the other'minor'antigens.
Ag 1 (urinary pre-albumin) and Ag 3 were detected in all samples of mouse dust studied. RAST and RAST inhibition also indicated the presence of urinary prealbumin. These findings suggest that the major mouse inhalant allergens may be derived predominantly from urine and secretions originating in the skin and present on the fur.     

Specific IgE antibodies in workers with occupational asthma due to western red cedar

The presence of specific IgE antibodies in the serum of patients with occupational asthma resulting from exposure to western red cedar (RCA) was studied by a radioallergosorbent test (RAST). The antigen matrix used in the RAST was either a conjugate of Sepharose particles with antigens in a crude cedar extract or with plicatic acid, the major haptenic component of cedar antigens. Of eighteen patients with clinical RCA and positive reaction to antigenic bronchoprovocation, eight were found to have abnormal RAST values. By appropriate absorption experiments, the serum RAST activity was shown to represent cedar antigen-specific IgE antibodies. No significant RAST activity was detected in the serum specimens from sixteen control subjects or from ten patients with negative bronchoprovocation-reaction to antigenic challenge. These results suggest that IgE antibody-mediated allergic reaction may be an important pathogenetic factor in RCA.     

Frequency of occurrence of IgG (S-TS)

A group of eighty-four sera from a selected population of patients suspected of hypersensitivity to food and environmental allergens was examined by both RAST and passive transfer in monkeys for IgE and IgG (S-TS) antibodies respectively. A high proportion (26%) showed IgG (S-TS) to milk, and this was more than four times the frequency (6%) for IgG (S-TS) to any other of the antigens tested. IgE and IgG (S-TS) antibodies behaved as independent biological systems.     

Coffee worker's asthma: A clinical appraisal using the radioallergosorbent test

Eight coffee workers with job-related respiratory symptoms were studied with water-soluble green coffee bean (GCB), castor bean (CaB), and factory dust (FD) antigens. Six workers described occupationally related asthma, rhinitis, conjunctivitis, and urticaria or pruritis and demonstrated positive wheal and flare skin tests with GCB and FD antigens. Serum radioallergosorbent test (RAST) indices ranged from 3 to 15 for GCB and 28 to 60 for CaB specificities. The other 2 coffee workers, who denied allergic symptoms, and 8 atopic and sex-matched control subjects demonstrated negative skin tests and RAST indices <2 with these same antigens. Provocative inhalation challenge (PIC) with GCB in 2 skin test-and RAST-positive subjects resulted in significant immediate asthmatic reactions, while PIC in a skin-and RAST-negative asthmatic subject failed to produce an airway response. GCB and CaB antigen characteristics and industrial sources were studied by RAST inhibition analysis. Lack of crossed RAST inhibition with GCB and CaB preparations showed these antigens to be distinct. Several industrial dust and sack samples produced significant RAST inhibition for GCB or CaB determinants. Chlorogenic acid produced no RAST inhibition for either determinant. The results indicated that coffee workers with occupational allergic disease demonstrate serum IgE antibodies specific for etiologic GCB and CaB antigens and that these antigens are distinct, unrelated to chlorogenic acid, present in certain industrial dust and sack samples, and capable of producing asthma in sensitized subjects.     

Inhibition of antibody-dependent allergic autocytotoxicity in rheumatoid arthritis by OM-89

Rheumatoid arthritis (RA) is a disease of multiple etiologies and clinical evidence suggests that a separate variant called "allergic arthritis" induced by food antigens could exist. A missing link in the confirmation of such an observation is a relative lack of a reliable in vitro assay which can confirm the in vivo oral ingestion challenge. Therefore, white blood cells (WBC) from 33 rheumatoid arthritis patients were separated and their disintegration was measured in the presence of specific IgE RAST positive sera and gluten-gliadin antigens. This assay was called the antibody-dependent allergic autocytotoxicity (ACT) test which represents an equivalent of an oral ingestion challenge with food antigens. Control WBC expressed 10-45% disintegration as compared to 75-95% in RA. Preincubation of WBC with OM-89 (immunomodulating fractions of Escherichia coli, OM Laboratories Ltd, Geneva, Switzerland) inhibited significantly antibody-dependent ACT in a dose-related manner (P less than 0.001) in our patients.     

Allergenic properties of rat urine and pelt extracts

We studied the relative diagnostic efficacy of skin tests and RAST assays in laboratory animal allergy in 16 rat-sensitive animal workers with the use of epithelial extract and urinary antigens from three inbred rat strains. RAST inhibition was used to evaluate possible urinary antigen-strain specificity. The urinary antigens were more reliable skin test and RAST reagents than were epithelial extracts; data from urinary antigen testing correlated better with historical data. RAST inhibition did not detect strain specificity among the urinary antigens. Antigens in rat urine appear to be of better diagnostic value than do epithelial extracts.