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.     

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.     

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.     

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.     

Basophil histamine release in children with adverse reactions to cow milk

Basophil histamine release was examined in 26 children suspected of having cow milk allergy (CMA). Following oral challenge with cow milk, the initial adverse reaction reappeared in 20 children, the majority developing urticaria. The urticaria patients showed a high degree of correlation between the results of histamine test, RAST and skin test. Children with gastrointestinal symptoms reacted to milk challenge, but only a few showed a positive histamine test, RAST and skin test. Among the patients with atopic dermatitis, the tests gave mostly negative results, which was in accordance with the lack of response to a milk challenge. The results obtained by removal from and fixation to the cell surface of IgE indicate an IgE-mediated reaction in CMA, which, in connection with the correlation between histamine test and RAST or skin test, suggests basophil histamine release as a suitable method for testing Type I allergy in children suspected of CMA.     

Mustard allergy in children

BACKGROUND: Mustard allergy is not well known. This study aimed to assess its clinical features and other associated allergies, and to define skin prick tests (SPT), specific IgE, and dose response by oral food challenge. METHODS: Our study investigated 36 children with positive mustard SPT. The diagnosis of mustard allergy was based on open or single-blind, placebo-controlled food challenge (SBPCFC). We compared the subjects to 22 controls. RESULTS: The initial clinical features were atopic dermatitis (51.8%), and urticaria and/or angioedema (37%). Fifteen children were allergic (positive SBPCFC) and 21 children were nonallergic (negative SBPCFC). Symptoms after mustard ingestion started under 3 years of age in 53.3% of the subjects. There was no significant difference in the food allergies and associated inhalant allergen sensitizations between the two groups. In the allergic group, the mean wheal diameter for mustard SPT was 8.8 mm and the median concentration of mustard serum (s) IgE 14.8 kU/l. The mean cumulative reactive dose were 153 mg. CONCLUSIONS: Allergic reactions to mustard started early in life. Clinical symptoms were not severe in children. Mustard should be included in screening tests of food allergy in children.     

The atopy patch test (APT)-- a useful tool for the diagnosis of food allergy in children with atopic dermatitis

BACKGROUND: While immediate-type clinical reactions to food can quite easily be identified by history or measurement of specific IgE in combination with positive oral food challenges, the evaluation of food allergy in the absence of immediate clinical reactions still presents diagnostic difficulties--particularly in children with atopic dermatitis. The objective of this study was to evaluate the diagnostic value of the atopy patch test (APT) with regard to late-phase reactions observed in double-blind, placebo-controlled food challenges with cow's milk, hen's egg, wheat, and soybean. METHODS: We investigated 75 children (median age 2.1 years) with suspected food allergy by double-blind, placebo-controlled food challenges, specific IgE in serum, skin prick test, and APT. Of the subjects, 69/75 suffered from atopic dermatitis. RESULTS: Of 209 oral challenges, 133 were performed with allergen and 76 with placebo. We assessed 77/133 allergen and 2/76 placebo challenges as positive. In 66 of 77 (86%) positive oral challenges, specific IgE in serum to the corresponding allergen was positive; in 64/77 (83%) the skin prick test, and in 42/77 (55%) the APT was positive. While immediate-type reactions were associated with positive skin prick test and proof of specific IgE in serum, late-phase clinical reactions were associated with a positive APT (sensitivity 76%, specificity 95%). CONCLUSIONS: The APT seems to be a valuable additional tool in the diagnostic work-up of food allergy in children with atopic dermatitis - especially with regard to late-phase clinical reactions. The APT may help to prevent unnecessary restrictive diets which may be the consequence of misjudging late reactions by clinical assessment alone.     

Differences in skin-prick and patch-test reactivity are related to the heterogeneity of atopic eczema in infants

Current data indicate an obvious relation between food allergy and atopic eczema in infants. However, diagnostic methods for food allergy need to be supplemented. The objective was to study the relevance of food patch testing in the detection of food allergy in correlation with oral food challenge and skin prick tests in atopic infants. Infants with atopic eczema (n = 113) aged 2–24 months were studied. Each patient was subjected to double-blind, placebo-controlled, or open cow's milk challenge, and skin prick and patch tests. Polysensitization, as judged from skin test results, was common in patients with atopic eczema (79/113). Cow's milk challenge was positive in 54/113 infants; reactions were immediate in 36/54 and delayed in 18/54. Immediate-type reactions were associated with skin prick test positivity and delayed reactions with patch test positivity. Altogether 26% of the cow's milk-allergic infants were detected by patch testing only. Patch testing improved the accuracy of skin testing in the diagnosis of food allergy in infants with atopic eczema, but it needs to be standardized. Polysensitization appears to be more common than generally believed among infants with atopic eczema.     

Placebo-controlled double-blind food challenge in asthma

To determine the prevalence of food allergy as a cause of exacerbation of asthma, we studied 300 consecutive patients with asthma (7 months to 80 years of age) who attended a respiratory clinic. Each patient was screened for possible food allergy by means of a questionnaire and by skin prick tests with the six food allergens most common in our area. Patients with either a suggestive history and/or a positive prick test and/or RAST underwent double-blind food challenge with lyophilized food in capsules or food mixed in a broth to disguise its taste. Pulmonary function tests and symptoms were followed for 8 hours after each challenge. Of the 300 patients screened, only 25 had either a history or skin prick tests or RAST responses suggestive of food allergy. Twenty patients had interpretable food challenges. In these 20 patients, food challenge caused asthma in six and caused other symptoms (atopic dermatitis and gastrointestinal symptoms) in five. On rechallenge after pretreatment with disodium cromoglycate (300 mg 30 minutes before the food challenge), the asthmatic response was blocked in four of five subjects. The patients with asthma with food allergy were generally young, had a current or past history of atopic dermatitis, and high total serum IgE levels. Our findings confirm that food allergy can elicit asthma, but its incidence is low, even in the population attending a specialty clinic. Food elimination diets should not be prescribed for all patients reporting an adverse reaction to foods or having a positive skin prick test and/or RAST with food allergens. In patients with asthma caused by food allergy, disodium cromoglycate may be used to complement elimination diets.     

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.     

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

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

Allergy to ingested cereals in atopic children

Clinical features, hypersensitivity mechanisms, and differential diagnosis of cereal allergy or intolerance were investigated in children with atopic dermatitis (AD). On oral provocation, 18 children exhibited a positive response to wheat, three to rye, one to barley, and one to oats. Cereal-induced symptoms were dermatologic, gastrointestinal, or oropharyngeal, and their onset after provocation was immediate (eight cases), delayed (14 cases), or both immediate and delayed (one case). A combination of type I allergy tests (prick test, RAST, and histamine-release test) detected all immediate reactors and 9/14 delayed reactors. Of the five subjects remaining negative in these tests, three were positive in the patch or lymphocyte-proliferation tests. Subjects with cereal allergy or intolerance frequently possessed IgE, IgA, and IgG antibodies against gliadin, but only one of these children was HLA-DR3-positive, and none had reticulin antibodies typical of celiac disease. Combining tests of immediate and delayed hypersensitivity can confirm allergy to cereals in a more reliable way. The coexistence of cereal allergy and celiac disease seems to be rare.     

Late onset reactions to oral food challenge are linked to low serum interleukin-10 concentrations in patients with atopic dermatitis and food allergy

BACKGROUND: Aberrant cytokine production in vitro has been associated with atopic disease. No study has as yet been made of the circulating cytokine profiles in atopic patients with food allergy in response to oral allergen challenge. OBJECTIVE: To assess the effect of oral allergen challenge on the serum cytokine concentrations in patients with atopic dermatitis and food allergy. METHODS: Serum concentrations of interleukin (IL)-10, transforming growth factor beta 1, IL-1ra, IL-6, IL-5, IL-4 and interferon (IFN)-gamma were measured before and after double-blind, placebo-controlled food challenges (DBPCFC) (n = 73). Before DBPCFC, combined skin prick and patch testing was performed for cow milk, egg, soybean and cereals, and production of IFNgamma, IL-4, IL-10 and tumour necrosis factor alpha (TNFalpha) was determined in supernatants of cultures of peripheral blood mononuclear cells (PBMCs) stimulated by cow milk. RESULTS: The oral food challenge triggered immediate onset exanthematous reactions in 22 cases and late onset eczematous reactions in 29. The late-reacting cases had more positive skin patch test and negative skin prick test reactivities with allergenic food, and they had lower serum IL10 concentrations than immediate-reacting cases. In challenge-positive cases, IL-10 concentrations increased from 2.9 (0.1-5.04) pg/mL to 3. 9 (1.2-8.3) pg/mL in response to DBPCFC, P = 0.05, median (interquartile ranges), but not in those tolerant to cow milk. PBMCs of patients with cow milk allergy but not of those tolerant to cow milk generated TNFalpha in response to cow milk in vitro. CONCLUSION: These results indicate that oral allergen challenge in atopic patients with food allergy triggers systemic release of IL-10. Patients with late onset reactions were found to have lower serum IL-10 concentrations than their immediate-reacting counterparts. Considering that IL-10 is an inhibitory cytokine of delayed-type hypersensitivity, low IL-10 in late-reacting patients may explain the high frequency of their positive skin patch tests combined with negative skin prick tests.     

Skin manifestations in food allergy

Skin manifestations represent the most often observed clinical symptoms in food allergy. Immediate symptoms are urticaria, angioedema and sudden erythema (flush). Delayed symptoms which can be observed are exanthema and exacerbation or worsening of eczema (most often atopic dermatitis). Since delayed symptoms are difficult to diagnose, oral provocation tests are often necessary for patients with a suspected late onset of symptoms upon food ingestion. There is evidence that besides specific IgE, specific T cells play a role in the deterioration of eczema in atopic dermatitis. Although urticarial skin lesions are most often observed upon oral provocation with a suspected food, the rate of IgE-mediated food allergy in acute or chronic urticaria is rather low. In some patients suffering from chronic urticaria, intolerance reactions are also suspected. Since no laboratory or skin tests are available yet for the identification of clinically relevant food additives causing urticaria, oral provocation tests are mandatory for these patients.     

Evaluation of allergy to soy in patients with atopic dermatitis older than 14 years of age

Atopic dermatitis is associated with food allergies. The aim of this study is to evaluate soy allergy in patients suffering from atopic dermatitis. Altogether 228 persons were included; specific IgE, skin prick tests, atopy patch tests, challenge tests with soy and history of soy allergy were evaluated. Soy allergy was confirmed in eight patients (3.5%, in four patients with worsening of atopic dermatitis, in four patients with oral allergy syndrome), sensitisation to soy was found in another 47 patients (20%) with no clinical manifestation after soy ingestion. Dependence was confirmed statistically between soy allergy and pollen allergy and soy sensitivity and pollen allergy. About 20% of patients suffering from atopic dermatitis are sensitised to soy. Clinical symptoms of soy allergy occur only in 3.5% of patients suffering from atopic dermatitis.     

Adverse reactions to food additives in children with atopic symptoms

In a multicenter study conducted at four Danish hospital pediatric departments, the parents of 472 consecutive children were informed of this project to determine the incidence of intolerance of food additives among children referred to an allergy clinic with symptoms of asthma, atopic dermatitis, rhinitis, or urticaria. After a 2-week period on an additive-free diet, the children were challenged with the eliminated additives. The food additives investigated were coloring agents, preservatives, citric acid, and flavoring agents. Carbonated "lemonade" containing the dissolved additives was used for the open challenge. Two doses were used: a low dose and a 10-fold higher dose. Gelatin capsules were used for a double-blind challenge. The children were 4–15 years old, and they were attending an outpatient pediatric clinic for the first time. Of the 379 patients who entered the study, 44 were excluded and 335 were subjected to open challenge. A total of 23 children developed positive reactions after the open challenge. Sixteen of these patients accepted the double-blind challenge, and six showed a positive reaction to preservatives (atopic dermatitis, asthma, rhinitis), coloring agents (atopic dermatitis, asthma, urticaria, gastrointestinal symptoms), and citric acid (atopic dermatitis, gastrointestinal symptoms). The incidence of intolerance of food additives was 2% (6/335), as based on the double-blind challenge, and 7% (23/335), as based on the open challenge with lemonade. Children with atopic skin symptoms had a statistically increased risk of a positive reaction. This may have consequences for the future clinical investigation of children with atopic cutaneous symptoms.     

The incidence of food allergy in atopic dermatitis]

To clarify the incidence of food allergy in atopic dermatitis, non-selected 226 cases with atopic dermatitis visited in our hospital were evaluated by oral food challenge tests based on masked food allergy. 181 of 200 cases except 26 cases dropped out showed a positive reaction to at least one challenge test, after their skin manifestations had been relieved by environmental control and elimination diets. In conclusion, the incidence of food allergy in atopic dermatitis was 90.5%, and egg allergy, cow's milk allergy, soy bean allergy, wheat allergy, rice allergy were 83.5%, 51.5%, 33.5%, 20.0%, 2.5% respectively in 200 cases.     

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.     

Lupin allergy in peanut-allergic children and teenagers

Background:  Lupin has now been introduced into food production in the UK. There is a concern that, on account of cross-reactivity, peanut-allergic children are at high risk for lupin allergy.
Aims:  To investigate the prevalence of lupin sensitization and allergy in children with peanut allergy compared with atopic controls.
Methods:  Children (<18 years) were recruited. Peanut-allergic subjects either had a convincing history of peanut allergy with diagnostic peanut skin prick test (SPT) or specific-immunoglobulin E (IgE) results or a positive food challenge. Control subjects were atopic but not peanut-allergic. All subjects had SPT to peanut and lupin. Sensitized subjects were offered a randomized, double-blind, placebo-controlled lupin challenge. Lupin allergy was defined as objective immediate hypersensitivity reaction at food challenge.
Results:  Forty-seven peanut-allergic children and 46 atopic controls were recruited. Sixteen peanut-allergic children were sensitized to lupin [34%, 95% confidence interval (CI): 21–49%]. Nine were challenged to lupin. Two reacted (itchy mouth and urticaria; itchy mouth and 20% drop in peak expiratory flow rate) giving a minimum prevalence of lupin allergy in peanut-allergic children of 4.0% (95% CI: 1–15%). Atopic controls were significantly ( P  = 0.001) less likely to be sensitized to lupin (4%, 95% CI: 1–15%) and had smaller wheals and serum-specific IgE results. None of the atopic controls reacted on lupin challenge, giving a rate of allergy in the atopic controls of 0% (95% CI: 0–8%).
Conclusions:  A small but significant number of children with peanut allergy are allergic to lupin. Sensitization to lupin is much rarer in nonpeanut-allergic atopic subjects.     

Cow's milk allergy: diagnostic accuracy of skin prick and patch tests and specific IgE

BACKGROUND: The objective of the present study was to evaluate the relevance of skin tests and the concentration of cow's milk-specific IgE antibodies in correlation with oral cow's milk challenge in infants with suspected cow's milk allergy. METHODS: The study material comprised 143 infants under the age of 2 years who had undergone a diagnostic elimination challenge because of suspected cow's milk allergy in 1996. Cow's milk-specific IgE was measured, and skin prick and patch tests were performed. RESULTS: Of the 143 oral cow's milk challenges performed, 72 (50%) were positive. Of the positive reactions, 22 involved immediate-type reactions. In 50 patients, delayed-onset reactions of eczematous or gastrointestinal type appeared. Of the infants with challenge-proven cow's milk allergy, 26% showed elevated IgE concentrations to cow's milk, 14% had a positive skin prick test, and 44% had a positive patch test for cow's milk. Interestingly, in most patch test-positive patients, the prick test for cow's milk was negative. CONCLUSIONS: Our study demonstrated that many patients with a negative prick test result had a positive patch test to cow's milk. The patch test was a more sensitive method than the prick test or RAST to detect cow's milk allergy in this study population. Our results indicate that patch testing will significantly increase the probability of early detection of cow's milk allergy. Confirmation of the diagnosis is essential in patients with negative test results but a clinical suspicion of food allergy, and in patch test-positive patients. For this purpose, the most reliable method is the elimination-challenge procedure.