Allergy diagnosis with the radioallergosorbent test: A comparison with the results of skin and provocation tests in an unselected group of children with asthma and hay fever

The radioallergosorbent test (RAST) has been used for in vitro diagnosis of asthma and hay fever in children as an integrated part of the routine procedure for allergy diagnosis. A positive RAST test was combined with a positive prick test in $\text{196}\text{235}$ (80 per cent) tests and with a positive provocation test in $\text{163}\text{182}$ (90 per cent) tests. When the provocation test was positive to dry pollen, the stock solution ($\text{1}\text{10}$ w./v. or 10,000 PNU) of the allergen extract RAST was quite often negative, a fact that explains the lower degree of correlation for a negative RAST test. A comparison between the prick test and the provocation test revealed a high proportion, $\text{54}\text{146}$ (37 per cent), of positive prick tests that could not be confirmed by the provocation test. RAST is a simple, reliable test for IgE antibodies that is very useful for in vitro diagnosis of atopic allergy on a routine basis. RAST is harmless and less traumatic than skin testing and therefore suitable for use even on very small children. The information obtained on the patient's hypersensitivity is more relevant than that from regular skin testing, probably comparable to skin test titration with selected allergens but not quite as good as provocation testing of the shock organ involved. Whenever a provocation test cannot be performed for each suspected allergen, an RAST test, possibly completed with a prick test, is recommended.     

Role of immediate food hypersensitivity in the pathogenesis of atopic dermatitis

Twenty-six children with atopic dermatitis and markedly elevated serum IgE concentrations were evaluated for clinical evidence of hypersensitivity to foods with double-blind placebo-controlled food challenges. Selection of foods for challenges was based on positive prick skin tests (>3 mm wheal) or a convincing history. At least one positive skin test to a food antigen was found in $\text{24}\text{26}$ patients. A total of 111 double-blind placebo-controlled challenges were performed in these children after suspect foods were eliminated from their diets for 10 to 14 days. There were 23 positive challenges in 15 children, 21 of which manifested as cutaneous symptoms, primarily pruritus and an erythematous macular and/or maculopapular rash involving 5% (or greater) of the body surface. In all, 14 children (54%) developed cutaneous symptoms after food challenges. All symptoms occurred within 10 min to 2 hr of challenge; nasal symptoms, mild wheezing, and gastrointestinal symptoms were seen in some children. No symptoms occurred in 104 placebo challenges. There were $\text{86}\text{111}$ clinically insignificant positive skin tests (77%) and three false-negative skin tests. These studies demonstrate that in some children with atopic dermatitis, immediate food hypersensitivity can provoke cutaneous pruritus and erythema, which leads to scratching and subsequent eczematoid lesions.     

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.     

Component-resolved diagnosis with recombinant allergens in patients with cherry allergy

BACKGROUND: In pollen-related food allergy, extracts for skin prick tests (SPTs) are often not standardized, and the test reliability is affected by false-negative reactions. OBJECTIVE: We sought to evaluate a panel of recombinant allergens (RAs) derived from one allergenic food for use in component-resolved in vivo diagnosis, taking cherry as a model food. METHODS: Seventy-nine subjects were included in the study: 24 Swiss patients (group 1) with a positive double-blind placebo-controlled food challenge result to cherries, 23 patients with birch pollen allergy but without cherry allergy (group 2), 23 nonatopic subjects (group 3), and 9 Spanish patients with a history of a cherry allergy (group 4). SPTs were performed in duplicate by using recombinant cherry allergens (Bet v 1-related allergen: recombinant (r) Pru av 1; profilin: rPru av 4; and lipid transfer protein: rPru av 3) in concentrations of 10, 50, and 100 microg/mL. Furthermore, IgE reactivity to rPru av 1, rPru av 4, and rPru av 3 was assessed by means of immunoblot analysis. RESULTS: SPT responses with rPru av 1, rPru av 4, and rPru av 3 were positive in 92%, 17%, and 4% of the patients in group 1; in 74%, 30%, and 0% of the patients in group 2; in 0%, 22%, and 89% of the patients in group 4; and negative for all nonatopic subjects (group 3). Thus the sensitivity of a positive SPT response to at least one of the 3 RAs was 96%. The specificities, negative predictive values, and positive predictive values with the 3 RAs were 100%, 96%, and 100% if calculated in relation to the nonatopic control group but 17%, 79%, and 60% when calculated in relation to the control group with birch pollen allergy. The correlation between SPT and immunoblotting results was excellent. Sensitization to rPru av 3 was associated with more severe symptoms than sensitization to rPru av 1. CONCLUSIONS: SPTs with RAs proved to be highly sensitive for diagnosis of cherry allergy. Component-resolved in vivo diagnosis with standardized amounts of stable RAs allows us to determine sensitization patterns directly, to correlate them with severity of clinical symptoms, and to analyze geographic differences.     

The relationship of serum immunoglobulin E,allergy skin tests,and smoking to respiratory disorders

In this study of a general population sample in Tucson, Ariz., smokers showed higher levels of serum IgE despite having a lower rate of allergy skin-test reactivity to common aeroallergens than nonsmokers. The prevalence of rhinitis was closely related to the level of serum IgE in atopic subjects regardless of smoking habits. In nonatopic smokers, elevated IgE levels were not associated with high rhinitis rates. However, high IgE levels in nonatopic smokers were related to increased rates of diagnosed asthma, wheeze, and chronic cough and/or sputum ($\text{C}\text{S}$). These relationships were especially striking in subjects over the age of 54. In older nonatopic smokers, reported prevalences of “chronic bronchitis” and of functional impairment also increased in relation to the level of serum IgE. Reduced ventilatory function showed this relationship to IgE only when accompanied by $\text{C}\text{S}$. It is suggested that the excess IgE related to smoking is qualitatively different than that found in subjects reacting to aeroallergens, is not important in the pathogenesis of upper respiratory tract disease, but may play a role in the development of some lower respiratory tract disorders.     

Prolonged type of food allergy]

OBJECT: Prevalence of food allergy is the most frequent during infancy, and it is gradually decreasing with age. We can not distinguish patients developing tolerance from those with persistent food allergy, therefore we are unable to advice patients accelerating the development of tolerance. To clarify the factors developing tolerance or intolerance, we conducted the following study. METHOD: Patients who were diagnosed as food allergy to hen's egg, or cow's milk or wheat in infancy by the definitive history of positive food allergic reactions or food provocation tests were recruited to this study. Patients were divided into two groups; one (prolonged group, n=27) is those who needed to eliminate some of the main offending foods even at the age of 6 years old and the other (tolerized group, n=37) is those who had released all main offending foods by the age of 6 years old. RESULT: The factors which distinguished the prolonged group from the tolerized group were the positive clinical history of the atopic dermatitis and its prolonged clinical course, past history of anaphylactic shock, and maximum number of offending foods in the past clinical history. The specific IgE against main antigens such as egg white, cow's milk and wheat in the tolerized group was lower compared to that in the prolonged group, whereas no significant difference was found in non specific IgE value, peripheral eosinophil counts, and specific IgE against other antigens. CONCLUSION: We could find the clinical factors discriminating food allergy patients against three major food allergen among children developing tolerance by the age of 6 years old form those without tolerance.     

Relation between IgG antibodies to foods and IgE antibodies to milk, egg, cat, dog and/or mite in a cross-sectional study

BACKGROUND: Because IgG antibodies to foods can be detected before IgE antibodies to inhalants, increased levels of IgG antibodies to foods might be used as a predictor of IgE-mediated allergy in initially nonatopic children. OBJECTIVE: To examine the cross-sectional relation between IgG to foods (i.e. mixture of wheat and rice, mixture of soybean and peanut, egg white, cow's milk, meat, orange and potato) and specific IgE to cat, dog, mite, milk and egg white in 1-year-old children. METHODS: All atopic children (n = 120; 58 with and 62 without eczema) and a random sample of the nonatopic children (n = 144) of the Bokaal study were tested on their IgG response to foods. The IgG results of the food assays were dichotomized high or low using the 66th centile as a cut-off value. RESULTS: Atopic children more often had high IgG levels to foods than nonatopic children. IgG to egg white (OR = 7.50) and mixture of wheat and rice (OR = 4.79) were most strongly associated with positive specific IgE. In a stepwise logistic regression analysis egg white, mixture of wheat and rice, and orange were selected (OR = 3.76, OR = 2.43, and OR = 2.11, respectively). In children without eczema higher levels of IgG to foods were still significantly associated with atopy, which was most prominent for egg white, orange and cow's milk. CONCLUSION: An increased IgG antibody level to foods, especially to egg white, orange, and mixture of wheat and rice, indicates an increased risk of having IgE to cat, dog, mite, egg and/or milk allergens, even in the noneczematous group. Therefore, in another prospective study we are currently investigating the usefulness of IgG in early identification, i.e. before IgE antibodies can be detected, of children with an increased risk of developing allergic diseases in the future.     

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.     

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.     

Immunologic evaluation of shrimp-allergic individuals

Thirty-three individuals with a history of immediate hypersensitivity reactions after shrimp ingestion and 29 nonshrimp-sensitive control subjects were evaluated for evidence of crustacea-specific immunity by skin prick test titration end point, RAST, and ELISA, with extracts of shrimp, crab, crayfish, and lobster. Individuals were categorized as either atopic or nonatopic on the basis of history and skin test reactivity to common inhalant allergens. Most (28/33) shrimp-sensitive subjects had positive skin prick tests to shrimp extract, whereas skin tests were negative in 27/29 control subjects. Eighty-one percent of atopic and 41% of nonatopic shrimp-sensitive subjects had elevated shrimp-RAST ratios. The RAST ratios of atopic individuals were significantly higher than ratios of nonatopic individuals, and there was a significant correlation between shrimp-RAST ratios and historical clinical symptom scores. RAST determinations of all control subjects were negative. Shrimp-sensitive subjects also had significantly elevated serum levels of shrimp-specific IgG and IgA as compared to control individuals. Both IgG and IgA shrimp-specific reactivity demonstrated a significant positive correlation with shrimp-RAST ratios. These studies indicate that IgE-mediated, type I mechanisms, detected by positive shrimp skin tests and RASTs, appear to be operative in crustacea-sensitive individuals, particularly those with concurrent respiratory allergy. Although the role of shrimp-specific IgG and IgA antibodies in the immunopathogenesis of crustacea allergy remains unclear, such antibodies appear to represent increased immunologic recognition of shrimp allergens/antigens in shrimp-sensitive subjects.     

Wheat allergy: a double-blind, placebo-controlled study in adults

BACKGROUND: Wheat is believed to be an uncommon cause of food allergy in adults; the number of studies that address IgE mediated wheat allergy in adults is all too few. OBJECTIVE: Determine how many subjects with a history of wheat allergy have real allergy by double-blind, placebo-controlled food challenge; identify the symptoms manifested during the challenge; determine the lowest provocation dose; determine the performance characteristics of wheat skin prick test and specific IgE; identify subjects with real wheat allergy for potential immunoblotting studies. METHODS: Patients underwent skin test with commercial wheat extract; specific wheat IgE was determined. Subjects were challenged with 25 g wheat. Subjects who were positive to raw wheat challenge underwent cooked wheat challenge. RESULTS: Thirty-seven double-blind placebo-controlled wheat challenges were performed on 27 patients. A total of 13 of 27 (48%) patients had a positive result. Eleven subjects with positive raw wheat challenge underwent cooked wheat challenge: 10 were positive. The provocation dose range was 0.1 to 25 g. Twenty-seven percent of the subjects allergic to wheat had a provocation dose that was < or =1.6 g. CONCLUSION: Wheat causes real food allergy in adults. More than a quarter of the patients allergic to wheat reacted to less than 1.6 g wheat. Specific IgE was more sensitive than skin test for wheat; however, specificity and predictive values were low for both tests. Thus, these tests should not be used to validate diagnosis of wheat allergy.     

Evaluation of Hymenoptera-sting sensitivity with deliberate sting challenges: inadequacy of present diagnostic methods

We administered deliberate sting challenges to 21 patients, five of whom had histories of large local (LL) reactions and 16 of whom had previous systemic (SYS) reactions to stings. Eleven had been treated previously with whole-body extract, but none had received venom immunotherapy. Immediately before sting challenges with honeybees, wasps, yellow jackets, yellow hornets, and white-faced hornets, we performed skin tests and measured serum IgE antibody levels with venoms from these five insects. In addition, we measured IgG antibody levels to honeybee, yellow jacket, and white-faced hornet venoms. In the LL group, $\text{14}\text{21}$ skin tests were negative, but in the SYS group $\text{30}\text{34}$ skin tests were positive prior to the deliberate sting. IgE antibody levels (expressed as percent of binding compared with serum from a nonsensitive individual) ranged from 63% to 789% and 66% to 801% for the LL and SYS groups, respectively. IgG antibodies ranged from <5 to 332 U/ml, and levels were similar for the LL and SYS groups. Fifty-five sting challenges were administered; seven generalized reactions were induced and occurred only in the SYS group. Seven individuals (three LL, four SYS) who tolerated the first series of stings returned for a second series of sting challenges with the same insects. Of these seven, $\text{10}\text{15}$ skin tests were now positive in the LL group; $\text{10}\text{12}$ skin tests were now positive in the SYS group. IgE antibody levels ranged from 103% to 737% and 85% to 2389% for the LL and SYS groups, respectively, prior to the second series of sting challenges; IgG antibody levels were again similar in both groups. All repeat challenges were tolerated without generalized reactions. No in vitro or in vivo test predicted with certainty the clinical immune status of a sting-sensitive person.     

In vivo and in vitro comparison of fire ant venom and fire ant whole body extract

Thirty-four patients with a history of immediate hypersensitivity to the sting of the imported fire ant were evaluated in a study designed to compare the diagnostic usefulness of fire ant whole body extract (WBE) preparations with that of fire ant venom (IFAV). Ninety-one percent ($\text{31}\text{34}$) of the hypersensitive patients skin tested with IFAV at a maximal concentration of 1:5 × 10³, $\text{v}\text{v}$, demonstrated a wheat equal to or greater than the histamine control. Fifty-three percent ($\text{18}\text{34}$) of the group were skin test positive to a WBE preparation. When the criteria for a positive skin test were relaxed, 82% of the hypersensitive group could be identified with the IFAWBE. A comparison of skin test results in sensitive patients revealed variability in the sensitivity of the WBE preparations utilized in the study. Leukocyte histamine release demonstrated a dose-response release of histamine with both IFAV and SIWBEa preparations. Specific venom antisera produced in rabbits identified a precipitin line of common identity in a gel-diffusion system containing IFAWBE and IFAV. This finding was verified by the competitive inhibition of IFAWBE with IFAV in a solid-phase radioimmunoassay system. Fire ant WBEs contain venom constituents and are effective diagnostic agents in up to 82% of patients with hypersensitivity to the sting of the imported fire ant. Marked variability in the responsiveness of sensitive patients to different WBE preparations mandates standardization of these diagnostic preparations.     

IgE binding to soluble and insoluble wheat flour proteins in atopic and non-atopic patients suffering from gastrointestinal symptoms after wheat ingestion

BACKGROUND: The involvement of IgE-mediated hypersensitivity reactions in the genesis of gastrointestinal symptoms after ingestion of foods containing wheat has been rarely reported. OBJECTIVE: To detect IgE specifically binding to wheat proteins in the sera of atopic and non-atopic patients suffering from gastrointestinal symptoms after ingestion of wheat and to evaluate the reliability of skin prick test and CAP in the diagnosis of food allergy to wheat. METHODS: The sera of patients (10 atopic and 10 non-atopic) previously diagnosed as suffering from irritable bowel syndrome and complaining of symptoms after wheat ingestion were analysed by immunoblotting for IgE binding to water/salt-soluble and insoluble wheat flour proteins. RESULTS: All the atopic patients and only one of the non-atopic patients were positive to wheat CAP. For the patients tested, skin prick test was positive for all the atopic patients and for only one of the non-atopic patients. However, immunoblotting experiments showed the presence of specific IgE to wheat proteins in all the patients. Ten out of 11 of the wheat CAP-positive patients had IgE binding to a soluble 16-kDa band, but the same band was recognized, in a slighter way, by only two out of nine of the wheat CAP-negative patients. Moreover, although almost all of the patients were negative in CAP testing with gluten, 19 out of 20 recognized protein bands belonging to the prolamin fraction. CONCLUSIONS: For the atopic patients the positivity to skin prick test and CAP to wheat was in accordance with the immunoblotting results and a food allergy to wheat could be diagnosed. In these patients a major allergen was a 16-kDa band corresponding to members of the cereal alpha-amylase/trypsin inhibitors protein family, the major allergens involved in baker's asthma. In the non-atopic patients the positive immunoblotting results contrasted with the responses of the allergologic tests, indicating that the allergenic wheat protein preparations currently used are of limited value in detecting specific IgE to wheat and that the fraction of irritable bowel syndrome (IBS) patients with food allergy may be larger than believed.     

IgE.IgG4 antibody in eczema in infants between 5-7 months of age. I. Relationship to the degree of eczema involvement]

Assessments have been made of serum IgE and IgA value, specific IgE and IgG4 antibody titers to foods, house dust, mite and percent peripheral++ eosinophil count in 191 infants with and without eczema between 5-7 months of age. Eczema patients were divided into 4 groups according to the degree of eczema involvement and laboratory data were compared between these and not eczematous group. The results were as follows; 1) IgE antibody titers were higher as the degree of eczema involvement increased. 2) RAST positive rates to foods increased with the degree of eczema involvement. Positive rate was highest to egg white followed by milk, soybean, wheat and rice. 3) Only 9 cases were RAST-positive to rice or wheat and all of them had IgE antibodies to other allergens tested. 4) A value of 10 IU/ml, which is the lowest measurable value of IgE in infants was considered to be a little too high to speculate allergy to some foods. 5) Specific IgG4 antibodies were positive only to milk. 6) All the 18 cases with positive milk-specific IgG4 antibody were all negative in milk-specific IgE antibody, and conversely all the 14 cases with positive milk-specific IgE antibody were negative in milk-specific IgG4 antibody. From these results, it was concluded that food allergy is related to the degree of eczema involvement in infants between 5-7 months of age.     

Predictors of positive food challenge outcome in non–IgE-mediated reactions to food in children with atopic dermatitis

BACKGROUND: Atopic dermatitis is frequently associated with food allergy. In general, clinically manifested food allergy is regarded as IgE mediated. However, there are some children with food allergy for whom IgE hypersensitivity cannot be proven. OBJECTIVE: The aim was to evaluate the percentage of children with positive double-blind, placebo-controlled food challenge (DBPCFC) results but without any proof of IgE sensitization and to characterize this subgroup of children. METHODS: Two hundred eight DBPCFCs were performed in 139 children (median age, 13 months) with atopic dermatitis and suspected food-related clinical symptoms. All children were subjected to skin prick tests (SPTs), determination of specific IgE, and atopy patch tests. RESULTS: One hundred eleven (53%) of 208 oral food challenge results were assessed as positive. Positive challenge results were separated into 2 groups according to IgE positivity: negative SPT and negative specific IgE results in serum (group A, n = 12) and positive SPT, specific IgE, or both results in serum (group B, n = 99). The atopy patch test results; the distribution of early, late, or both clinical reactions; the age of the children; and the total IgE levels all showed no significant differences between the 2 groups. However, wheat challenge results were more often positive among the apparently non-IgE-sensitized children, and hen's egg challenge results were more often positive in the sensitized group (P < .05). CONCLUSION: Around 10% of positive DBPCFC results are not IgE mediated. Therefore not the proof of specific IgE but the suspicion of food-related symptoms should be the indication to perform oral food challenges, especially in the case of wheat. Otherwise, some children will not receive diagnoses for food allergy and be denied the benefits of a specific diet.     

Histologic studies of human skin test responses to ragweed, compound 48-80, and histamine

The patterns of mast cell and eosinophil changes at the site of intradermal injection of ragweed, compound $\text{48}\text{80}$, and histamine were studied by histologic techniques. Dermal biopsies of 23 ragweed skin test-positive subjects revealed increasing numbers of eosinophils and decreasing numbers of mast cells over a 240 minute period following injection of antigen. The eosinophil response began in the periappendigeal areas, extended into the interstitium, and occurred in sites with depressed wheal reactions in hydroxyzine-treated subjects. These cellular patterns did not occur at ragweed skin test sites in nonatopic subjects. However, compound $\text{48}\text{80}$ induced similar eosinophilic responses in both atopics and nonatopics. Histamine injection was followed by no eosinophilic or mast cell changes. These findings support the hypothesis that eosinophil responses in reagin-mediated reactions may occur secondary to release of a mediator other than histamine of mast cell origin.     

Public perception of food allergy

BACKGROUND: Although studies that use the double-blind placebo-controlled food challenge suggest that the prevalence of food allergy is about 2%, public belief in food allergy appears to be considerably higher. OBJECTIVE: The study was undertaken to determine the magnitude and features of the American public’s belief in food allergy by surveying a large, demographically balanced population. METHODS: A simple question about food allergy was incorporated into a broad, self-reported, mailed consumer questionnaire. Five thousand demographically representative American households were surveyed by means of quota sample in 1989, 1992, and 1993. RESULTS: The response rates were 79%, 75%, and 74%, respectively. Of responding households, 16.2%, 16.6%, and 13.9%, respectively, reported an average of 1.17 household members with food allergy. Individuals reported to be allergic to foods were more likely to be female, particularly adult women. Male individuals with reported food allergy tended to be young, whereas no such skew was noted among female subjects. Geographic differences were observed in reported food allergy, with the highest rate in the Pacific region. Milk and chocolate were the individual foods most frequently implicated in food allergy. Trends were consistent over the period studied. CONCLUSIONS: Perceived food allergy is widespread and persistent. The characteristics and demographic patterns of this belief are not reflective of known food allergy epidemiology derived from studies in which the double-blind placebo-controlled food challenge is used. (J ALLERGY CLIN IMMUNOL 1996;97:1247-51.)     

Evaluation of food allergy to wheat,cow milk,egg, soy and peanuts in patients suffering from atopic dermatitis

Few large studies concerning the importance of food allergy in adolescents and adult patients with atopic dermatitis exist. The evaluation of food allergy to egg white and yolk, peanuts, soy, cow milk and wheat in patients suffering from atopic dermatitis. Two hundred forty patients (70 men, 170 women) were examined. Complete dermatological and allergological examination was performed in all patients, including specific IgE, skin prick test and atopy patch test. The challenge test was performed according to the results of examinations with suspected foods. The food allergy to peanuts was confirmed in 20% of patients, to egg in 6%, to soy in 3.3%, to wheat in 2.5% and to milk in 0.8% – altogether in 65 patients (27.5%). The positive results in examinations without clinical symptoms of food allergy were recorded in another 78 patients (32.5%). The diagnostic work-up should comprise not only the laboratory methods, but also the diagnostic hypoallergenic diet and the challenge test.     

Recognition of food-allergic patients and their allergens by the RAST technique and clinical investigation

Sera from 119 patients with possible food allergies were tested against a panel of thirteen food allergens by the RAST technique. The results were compared with in vivo tests. 79% of foods causing symptoms gave a positive RAST to the specific food. Symptoms were grouped according to their time of appearance after taking the food; ‘immediate’ up to 1 hr and ‘non-immediate’ more than 1 hr afterwards. Almost all those with ‘immediate’ symptoms were already aware of the foods causing them and there was a 100% correlation of the RAST result with these. Only a few of those with ‘non-immediate’ symptoms were previously aware that these foods were responsible, and 64% of these gave a positive RAST. The majority of patients with a positive RAST result had total IgE in excess of 300 u/ml, had specific IgE antibodies against one or more common inhalant allergens, were under the age of 30 years and had a combination of asthma and eczema. We found the RAST method a useful and safe guide upon which to base a clinical investigation of food allergy, especially for patients whose symptoms appeared more than 1 hr after the food and in whom the relationship between their symptoms and food was not apparent. The RAST technique was surprisingly successful in identifying the foods which caused these ‘non-immediate’ symptoms.