Food allergy in infancy

Shaping of infant B cell receptor repertoires by environmental factors and infectious disease

Antigenic exposures at epithelial sites in infancy and early childhood are thought to influence the maturation of humoral immunity and modulate the risk of developing immunoglobulin E (IgE)-mediated allergic disease. How different kinds of environmental exposures influence B cell isotype switching to IgE, IgG, or IgA, and the somatic mutation maturation of these antibody pools, is not fully understood. We sequenced antibody repertoires in longitudinal blood samples in a birth cohort from infancy through the first 3 years of life and found that, whereas IgG and IgA show linear increases in mutational maturation with age, IgM and IgD mutations are more closely tied to pathogen exposure. IgE mutation frequencies are primarily increased in children with impaired skin barrier conditions such as eczema, suggesting that IgE affinity maturation could provide a mechanistic link between epithelial barrier failure and allergy development.

Component-Resolved Diagnosis in Food Allergies

Component-resolved diagnostics (CRD) in food allergies is an approach utilized to characterize the molecular components of each allergen involved in a specific IgE (sIgE)-mediated response. In the clinical practice, CRD can improve diagnostic accuracy and assist the physician in many aspects of the allergy work-up. CRD allows for discriminatory co-sensitization versus cross-sensitization phenomena and can be useful to stratify the clinical risk associated with a specific sensitization pattern, in addition to the oral food challenge (OFC). Despite this, there are still some unmet needs, such as the risk of over-prescribing unnecessary elimination diets and adrenaline auto-injectors. Moreover, up until now, none of the identified sIgE cutoff have shown a specificity and sensitivity profile as accurate as the OFC, which is the gold standard in diagnosing food allergies. In light of this, the aim of this review is to summarize the most relevant concepts in the field of CRD in food allergy and to provide a practical approach useful in clinical practice.

Milk and soy allergy

Cow's milk allergy (CMA) affects 2% to 3% of young children and presents with a wide range of IgE and non-IgE-mediated clinical syndromes, which have a significant economic and lifestyle effect. It is logical that a review of CMA would be linked to a review of soy allergy because soy formula is often an alternative source of nutrition for infants who do not tolerate cow's milk. This review examines the epidemiology, pathogenesis, clinical features, natural history, and diagnosis of cow's milk and soy allergy. Cross-reactivity and management of milk allergy are also discussed.

Predictive value of the cow's milk skin prick test in infantile colic

BACKGROUND AND OBJECTIVES

Infantile colic is a common problem among young infants. Cow's milk allergy has been suggested as one of the causes. We aimed to investigate the value of the cow's milk skin test for the diagnosis of cow's milk allergy in exclusively breast-fed infants with infantile colic.

METHODS

Exclusively breast-fed infants with infantile colic were enrolled in this study. On the first visit, the average hours of crying of the infant in a 24-h period were recorded and the cow's milk skin test was performed. If the infant had a positive skin test, elimination of cow's milk from the mothers' diet was advised. Infants with negative skin tests were divided into case and control groups. Cow's milk was eliminated from the diet of mothers in the case group. After 2 weeks, the number of hours of crying were recorded again. The reduction in the crying hours was compared between the two groups using the chi-square test.

RESULTS

Skin tests were positive in 3 of 114 cases (2.6%) of infantile colic. All three cases recovered completely following elimination of cow's milk from the mother's diet. Among the 111 patients with negative skin tests, 77 patients completed the study: 35 in the case group and 42 in the control group. The reduction in crying hours in infants in the case group was not significantly different from that in the control group.

CONCLUSION

Elimination of cow's milk from the mothers' diet is not beneficial for infants with a negative skin test. Infants with a positive skin test may benefit from this management.

Micro-arrayed wheat seed and grass pollen allergens for component-resolved diagnosis

BACKGROUND

Wheat is a potent allergen source and can cause baker's asthma, food and pollen allergy. The aim of the study was to develop an allergen micro-array for differential diagnosis of baker's asthma, wheat-induced food allergy and grass pollen allergy.

METHODS

We analysed the immunoglobulin-E reactivity profiles of patients suffering from baker's asthma, wheat-induced food allergy and grass pollen allergy to micro-arrayed recombinant wheat flour allergens and grass pollen allergens and compared these results with clinical results and diagnostic tests based on crude wheat flour, wheat pollen and grass pollen allergen extracts.

RESULTS

We identified recombinant wheat flour allergens, which are specifically recognized by patients suffering from baker's asthma, but not from patients with food allergy to wheat or pollen allergy. rPhl p 1 and rPhl p 5 were identified as marker allergens specific for grass pollen allergy. They can be used to replace grass pollen extracts for allergy diagnosis and to identify grass pollen allergic patients among patients suffering from baker's asthma and wheat-induced food allergy. Profilin was identified as a cross-reactive allergen recognized by patients suffering from baker's asthma, food and pollen allergy.

CONCLUSIONS

Our results indicate that it will be possible to design serological tests based on micro-arrayed recombinant wheat seed and grass pollen allergens for the discrimination of baker's asthma, wheat-induced food allergy and grass pollen allergy.

IgE-mediated food allergy diagnosis: Current status and new perspectives

In June 2005, the work of the EU Integrated Project EuroPrevall was started. EuroPrevall is the largest research project on food allergy ever performed in Europe. Major aims of the project are to generate for the first time reliable data on the prevalence of food allergies across Europe and on the natural course of food allergy development in infants. Improvement of in vitro diagnosis of food allergies is another important aim of the project. The present review summarizes current knowledge about the clinical presentation of food allergy and critically reviews available diagnostic tools at the beginning of the project period. A major problem in diagnosis is a relatively poor 'clinical specificity', i. e. both positive skin tests and in vitro tests for specific IgE are frequent in sensitized subjects without food allergy symptoms. So far, no in vitro test reliably predicts clinical food allergy. EuroPrevall aims at improving the predictive value of such tests by proceeding from diagnosis based on allergen extracts to purified allergen molecules, taking into account the affinity of the IgE-allergen interaction, and evaluating the potential of biological in vitro tests such as histamine release tests or basophil activation tests including assays performed with permanently growing cell lines.

Maternal smoking and infantile gastrointestinal dysregulation: the case of colic

BACKGROUND

Infants' healthy growth and development are predicated, in part, on regular functioning of the gastrointestinal (GI) tract. In the first 6 months of life, infants typically double their birth weights. During this period of intense growth, the GI tract needs to be highly active and to function optimally. Identifying modifiable causes of GI tract dysregulation is important for understanding the pathophysiologic processes of such dysregulation, for identifying effective and efficient interventions, and for developing early prevention and health promotion strategies. One such modifiable cause seems to be maternal smoking, both during and after pregnancy. Purpose. This article brings together information that strongly suggests that infants' exposure to tobacco smoke is linked to elevated blood motilin levels, which in turn are linked to an increased risk of GI dysregulation, including colic and acid reflux. We base this hypothesis on evidence supporting a link between maternal smoking and infantile colic (IC) and on additional evidence proposing increased motilin release, attributable to exposure to tobacco smoke and its metabolites, as a physiologic mechanism linking maternal smoking with infantile GI dysregulation.

METHODS

We critically review and synthesize epidemiologic, physiologic, and biological evidence pertaining to smoking and colic, smoking and motilin levels, and motilin and colic.

RESULTS

Six studies have investigated the link between maternal smoking and IC, but IC was defined according to Wessel's rule of threes (crying for > or =3 hours per day, > or =3 days per week, for > or =3 weeks) in only 1 of these studies. The remaining studies used definitions that ranged from less-stringent variations of Wessel's criteria to definitions that would suggest excessive crying but not necessarily colic. Results from 5 of these studies suggest that there is an independent association between maternal smoking and excessive crying, as well as IC. Recent studies of the GI system provide strong, but indirect, corroborating evidence suggesting physiologic pathways through which maternal smoking can be linked to IC. This physiologic evidence can be outlined as follows: (1) smoking is linked to increased plasma and intestinal motilin levels and (2) higher-than-average levels of motilin are linked to elevated risks of IC. Although these findings from disparate fields suggest a physiologic mechanism linking maternal smoking with IC, the entire chain of events has not been examined in a single cohort. A prospective study, begun in pregnancy and continuing through the first 4 months of life, could provide definitive evidence linking these disparate lines of research. Key points for such a study are considered.

CONCLUSIONS

New epidemiologic evidence suggests that exposure to cigarette smoke and its metabolites may be linked to IC. Moreover, studies of the GI system provide corroborating evidence that suggests that (1) smoking is linked to increased plasma and intestinal motilin levels and (2) higher-than-average intestinal motilin levels are linked to elevated risks of IC. In the United States, nearly one-half of all women smokers continue to smoke during their pregnancies. This amounts to approximately 12% of all women who give birth. Moreover, it is estimated that 50% to 80% of employed adults have regular exposure to environmental tobacco smoke and that >30% of nonsmokers live with smokers. If, as we suspect, exposure to cigarette smoke increases the risk of colic, then this would provide additional incentives to parents to abstain from smoking. Decreased exposure to tobacco smoke can be expected to provide widespread and long-term health benefits to maternal and child populations.

The relationship of allergen-specific IgE levels and oral food challenge outcome

BACKGROUND

Oral food challenges remain the gold standard for the diagnosis of food allergy. However, clear clinical and laboratory guidelines have not been firmly established to determine when oral challenges should be performed.

OBJECTIVE

We sought to determine the value of food-specific IgE levels in predicting challenge outcome.

METHODS

A retrospective chart review of 604 food challenges in 391 children was performed. All children had food-specific IgE levels measured by means of CAP-RAST before challenge. Data were analyzed to determine the relationship between food-specific IgE levels and challenge outcome, as well as the relationship between other clinical parameters and challenge outcome.

RESULTS

Forty-five percent of milk challenges were passed compared with 57% for egg, 59% for peanut, 67% for wheat, and 72% for soy. Specific IgE levels were higher among patients who failed challenges than among those who passed (P </=.03 for each food). When seeking a specific IgE level at which a 50% pass rate could be expected, a cutoff level of 2 kUA/L was determined for milk, egg, and peanut. Data were less clear for wheat and soy. Coexistent eczema or asthma was associated with failed egg challenges, but other atopic disease was otherwise not associated with challenge outcome.

CONCLUSIONS

Allergen-specific IgE concentrations to milk, egg, and peanut and, to a lesser extent, wheat and soy serve as useful predictors of challenge outcome and should be considered when selecting patients for oral challenge to these foods.

[Epidemiology of food allergies]

Difficulties resulting from diagnosis of food allergies show an impact on the validity of epidemiological data, which are mainly based on questionnaire data or results from allergy tests for evidence of specific IgE antibodies. The frequency of self-reported adverse food reactions in population based studies ranges between 5% and 33% with women reporting a higher frequency of such reactions. Only two epidemiological studies have performed double blind, placebo-controlled oral food challenge tests. Extrapolating these results, the prevalence of food allergies is estimated at 2% within the general population. An epidemiological questionnaire-based study in France reports on 3.5% of the general population suffering from food allergies. According to studies of the Allergy Ward in Zürich, in 46-60% of all cases skin and mucosa are predominantly affected, with oral allergy syndrome and urticaria being the most frequent manifestations. A food allergy is significantly associated with different manifestations of atopy and predominantly to hay fever, atopic eczema, urticaria and asthma.

Management of bovine protein allergy: new perspectives and nutritional aspects

OBJECTIVES

Awareness of the considerable incidence of bovine protein allergy in infancy makes it necessary to eliminate cow's milk antigens from the diet in special cases. The primary objective of this review is to discuss the nutritional aspects and appropriate use of hypoallergenic formulas as a substitute for cow's milk formulas and to present new alternative feeding modalities in this field.

DATA SOURCES

Related articles in PubMed (National Library of Medicine) were reviewed. This review is a synthesis of these sources along with the discussions with experts in this field and the expert opinion of the authors.

RESULTS

Soy protein-based and hydrolyzed milk protein formulas are the most commonly used alternative protein sources in the case of bovine protein allergy. Despite the adequacy of their nutritional values, there are still some problems to be solved regarding these formulas. In addition, a considerable percentage of the infants with bovine protein allergy may also present allergenic reactions to soy proteins as well as to hydrolyzed milk proteins. Thus, there still exists chaos in the selection of the most appropriate formula for infants sensitized to cow's milk protein. Rice protein-based formulas, probiotics, and prebiotics are expected to be new effective alternatives.

CONCLUSIONS

Bovine protein allergy constitutes an important place in childhood food allergies. Soy protein-based and hydrolyzed protein formulas have some disadvantages and risk of allergenic activity that is not to be underestimated. So, substitution of cow's milk protein with an alternative protein source in sensitized infants has become an art rather than a science. Rice protein, prebiotics, and probiotics appear to be valuable alternatives giving hope for the future.

Accuracy of skin prick tests in IgE-mediated adverse reactions to bovine proteins

OBJECTIVES

To review the recent literature on the diagnostic accuracy of skin prick tests (SPTs) in pediatric food allergy, focusing on adverse reactions to milk and beef. To present data about the test performance characteristics of beef extracts used in SPTs among children with atopic dermatitis (AD) reporting immediate hypersensitivity to beef.

DATA SOURCES

MEDLINE search using the following algorithm ["skin prick test" AND "food allergy" OR allergen; 1997-2002; English; all children]. Prospective sensitivity study of SPTs in 34 patients.

STUDY SELECTION

Thirty-four children with AD (median age 2.29 years) were consecutively recruited between 1992 and 2000 because of immediate reactions to beef. On double-blind, placebo-controlled food challenges (entry criterion), 20 of the patients reacted to beef and 14 did not. Cut-off points for skin prick test wheal positivity was selected by receiving-operator characteristic analysis for fresh and commercial beef allergens. Sensitivity and specificity of skin tests and indices of reproducibility were calculated.

RESULTS

In the literature, the positive predictive accuracies of skin prick tests vary between 69 and 100% and the negative predictive accuracies between 20 to 86% for cow's milk. In our series, SPTs with commercial beef extracts were highly diagnostic (100% sensitivity; 10% false positive rate) and SPTs with fresh beef were highly specific (100%), albeit with a false-positive rate of 21.42%.

CONCLUSIONS

From the literature, we conclude that the diagnostic accuracy of SPTs with milk should be reappraised in the workup of cow's milk allergy. Carrying out commercial and fresh food SPTs at the same time substantially reduces costs and diagnostic work. Oral provocation is necessary in 20.68% of children with AD who have immediate symptoms to beef. Greater allergen standardization and streamlining of the workup of cow's milk allergy are desirable future goals.

Specificity of allergen skin testing in predicting positive open food challenges to milk, egg and peanut in children

BACKGROUND

The specificity of allergen skin prick testing to diagnose clinically relevant food allergy is controversial.

OBJECTIVES

To determine the specificity of the allergen weal diameter to correctly identify children who react on formal open food challenges.

METHODS

Over a 9-year period children referred to a tertiary allergy clinic for the evaluation of suspected food allergy were prospectively studied. Allergen skin prick testing to cow milk, egg white and peanut extracts (Dome-Hollister-Stier, Spokane, WA, USA) was undertaken using a lancet technique. All children underwent open food challenges to the relevant food(s) in a hospital clinic. Challenges were classified as positive, if objective signs were seen; negative, if the child could tolerate normal quantities of the food, daily, for one week; or inconclusive if none of the former criteria were met.

RESULTS

Five hundred and fifty-five challenges were undertaken in 467 children: 339 challenges to cow milk, 121 to egg, and 95 to peanut. Fifty-five percentage of challenges were positive, 37% negative, and 8% inconclusive. For each food it was possible to identify a skin weal diameter at, and above, which negative reactions did not occur: cow milk, 8 mm; egg, 7 mm; peanut, 8 mm. In contrast, positive reactions could occur with a skin wheal diameter of 0 mm.

CONCLUSIONS

In this high risk referral population it was possible to define skin weal diameters to egg, milk and peanut above which open oral food challenges were positive (100% specificity). By utilizing these measurements the need for formal food challenges can be reduced.

Criteria to determine food allergen priority

The emergent health issue of food allergens presents an important challenge to the food industry. More than 170 foods have been reported in the scientific literature as causing allergic reactions. Clearly, it would be impossible to deal with the presence of trace amounts of all these in the context of food labeling. If the decision to classify major allergens is based solely on the knowledge and experience of allergists and food scientists in the field, without scientifically defined criteria, it is likely to lead to a proliferation of lists. Such practices may lead to an unnecessary elimination of foods containing important nutrients. This paper defines food allergy, food intolerance, and food anaphylaxis and identifies criteria for classifying food allergens associated with frequent allergic reactions. A practical list of food allergens that may result in potentially life-threatening allergic reactions is provided. A mechanism-based (i.e., immunoglobulin E mediated), acute life-threatening anaphylaxis that is standardized and measurable and reflects the severity of health risk is proposed as the principal inclusion criterion for food allergen labeling. Where available, prevalence in the population and threshold levels of allergens should be used as an additional guide to identify possible future labeling needs.

Infant feeding patterns affect the subsequent immunological features in cow's milk allergy

BACKGROUND

The first exposure to food antigens provokes an immune reaction in an infant, its type depending on the quantity and frequency of doses and the age at introduction, and also being influenced by genetic factors. Most infants develop tolerance to food antigens, but in a small minority they provoke adverse symptoms.

OBJECTIVE

To study the effects of breast and formula feeding and other environmental and genetic factors on the subsequent type of cow's milk allergy classified by the presence or absence of immunoglobulin (Ig) E antibodies to cow's milk.

METHODS

A cohort of 6209 infants was followed prospectively from birth for symptoms of cow's milk allergy. The infant-feeding regimen was recorded at the maternity hospital and at home. At a mean age of 6.7 months, a total of 118 infants (1.9%) reacted adversely to a challenge with cow's milk. Before the challenge, the response to a skin-prick test with cow's milk and serum IgE cow's milk antibodies was measured.

RESULTS

At challenge, 75 (64%) infants showed IgE-positive reactions to cow's milk, their most common symptom being acute-onset urticaria. Significant risk factors for the presence of IgE cow's milk antibodies in allergic infants were long breast-feeding (odds ratio [OR] 3.9, 95% confidence interval [CI] 1.6-9.8), exposure to cow's milk at the maternity hospital (OR 3.5, 95% CI 1.2-10.1) and breast-feeding during the first 2 months at home either exclusively (OR 5.1, 95% CI 1.6-16.4) or combined with infrequent exposure to small amounts of cow's milk (OR 5.7, 95% CI 1.5-21.6). Fifty infants had their first adverse symptoms during exclusive breast-feeding, and 32 infants were sensitized during exclusive breast-feeding. Most of the infants in both cases were IgE-positive: 37 and 23, respectively.

CONCLUSIONS

In infants who are prone to developing cow's milk allergy, prolonged breast-feeding exclusively or combined with infrequent exposure to small amounts of cow's milk during the first 2 months of life induces development of IgE-mediated response to cow's milk.

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.

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.

Effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food and inhalant allergens during the first 3 years of life. Multicenter Allergy Study Group, Germany

BACKGROUND

The study aimed to assess the effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food allergens and inhalant allergens during the first 3 years of life.

METHODS

A total of 342 children of a prospective and observational birth cohort study on atopy (MAS) were included on the basis of a complete follow-up of specific IgE measurements at the ages of 1, 2, and 3 years with available questionnaire information about the parental smoking habit at birth, 18 months, and 3 years of age. Study children were grouped into four exposure categories representing in utero and postnatal environmental tobacco smoke (ETS) exposure, and according to the number of cigarettes smoked by the parents. The effect on the development of allergic sensitization to food, outdoor, and indoor allergens by 3 years of age was determined by multiple logistic regression analyses.

RESULTS

At the age of 3, children who were pre- and postnatally exposed to tobacco smoke had a significantly higher risk of sensitization to food allergens (odds ratio: 2.3, 95% C.I.: 1.1-4.6) than unexposed children. Children who were only postnatally exposed by a smoking mother also had a 2.2 times higher risk (95% C.I.: 0.9-5.9) of sensitization than unexposed children. These two categories (pre- and/or postnatal exposure) contribute to the significant overall effect of the tobacco smoke exposure (P< or =0.02). No significant association between tobacco smoke exposure and specific sensitization to inhalant allergens was observed. The determining risk factors for this type of sensitization were atopic family history and mite- and cat-allergen exposure levels.

CONCLUSIONS

During the first 3 years of life, both prenatal and postnatal tobacco smoke exposure has an adjuvant effect on allergic sensitization which seems to be restricted to allergens to which children are mainly exposed, in combination with the peak of the ETS exposure around the first birthday.

The rising trends in asthma and allergic disease

Considerable variation in the prevalence of childhood asthma and allergic conditions has been shown in previous studies. These differences may in part be attributable to methodological problems in defining childhood asthma and wheezing illnesses. However, the results of recent surveys using identical study instruments suggest that the variation in the distribution of the disease is real. In western societies serial prevalence studies have furthermore shown an increasing trend in the prevalence of childhood asthma and airway hyperresponsiveness. A concomitant increase in the prevalence of hay fever and atopic eczema has been reported by others. Moreover, hospitalization rates for childhood wheezing illnesses have increased in affluent countries suggesting that indeed the morbidity from these causes has increased in the last decades. Interestingly, areas of low prevalence of asthma and atopic conditions have recently been identified in developing countries and in Eastern Europe. In Eastern Germany where drastic changes towards westernization of living conditions have occurred after reunification an increase in the prevalence of hay fever and atopic sensitization has been documented over the last 4-5 years in children aged between 9 and 10 years of age. The prevalence of asthma and airway hyperresponsiveness, however, remained virtually unchanged in this age group. These children spent their first 3 years of life under socialist living conditions and were exposed to a western lifestyle only after their third birthday. Therefore, environmental factors may affect an individual's inherited susceptibility for the development of asthma and hay fever at different ages inducing changes in the prevalence of atopic diseases in populations in a time- and age-dependent way.

Diagnostic tests in children with atopic dermatitis and food allergy

BACKGROUND

Skin testing is a common diagnostic procedure in food allergy. The skin prick test is the test of first choice for investigating the immediate IgE-mediated reaction. The skin application food test (SAFT) has been developed on the basis of the mechanism of the contact urticaria syndrome (CUS).

METHODS

We studied the relevance of the SAFT in children younger than 4 years with atopic dermatitis and (suspected) food allergy as compared with the prick-prick test, the radioallergosorbent test (RAST), and the oral challenge. In the skin tests, we used fresh food, in the same state as it was consumed.

RESULTS

There was a good agreement between the SAFT and the prick-prick test. A moderate agreement was observed between the SAFT and the serologic test (RAST). Significantly more positive results in the RAST were observed than in the SAFT. There was very good agreement between the SAFT and the oral challenge (kappa = 0.86).

CONCLUSIONS

The SAFT is a reliable and child-friendly skin test for evaluating (suspected) food allergy in children younger than 4 years with atopic dermatitis. The very good correlation with the oral challenge indicates that one may probably consider the SAFT a "skin provocation" in children younger than 4 years.

Long-lasting sensitization to food during the first two years precedes allergic airway disease. The MAS Study Group, Germany

The purpose of the study was to investigate whether the duration of sensitization to food allergens during early childhood is related to later development of IgE mediated hypersensitivity to inhalant allergens and of allergic rhinitis and asthma in 5-year-old children and whether long-lasting food-sensitization may be used to predict subsequent allergic airway diseases. Five hundred and eight children of a prospective birth cohort study with available serum samples at one and two years of age were included and followed up until five years of age. Specific sensitization to food and inhalant allergens and the occurrence of subsequent allergic airway diseases were determined. Children with a long-lasting sensitization to food allergens (persistently sensitized for more than one year) produced significantly higher total IgE and specific IgE levels than children who were only transiently food-sensitized by two years of age. Children persistently sensitized to food had a 3.4 fold higher risk of developing allergic rhinitis and a 5.5 fold higher risk of developing asthma than infants who were only transiently food sensitized. Persistent food sensitization in combination with a positive atopic family history was a strong predictor for the development of allergic rhinitis and asthma at five years of age. The risks for these children are up to 50%, and 67% respectively. Persistently detectable sensitization to food over more than one year in early childhood is a strong prognostic factor for subsequent allergic airway disease. Persistently food-sensitized children especially in atopic families have to be regarded as a high-risk group and should be considered for preventive measures against respiratory atopy.

Effects of parity and weaning practices on breastfeeding duration

The purpose of this project was to examine (a) patterns of breastfeeding and (b) duration with parity and breastfeeding experience, and (c) mothers' reasons for termination of breastfeeding. A convenience sample of 120 breastfeeding mothers was followed by home visits and telephone for 20 weeks after delivery. The sample consisted of 69 primiparas, 40 multiparas with previous breastfeeding experience, and 11 multiparas with no prior breastfeeding experience. Parity was not significantly associated with the continuation of breastfeeding but there was a trend toward a difference made by breastfeeding experience. Inadequate milk supply and employment were the two most common reasons reported for weaning. Implications for support in the workplace and for first-time breastfeeding mothers are discussed.

Adult onset of cow's milk protein allergy with small-intestinal mucosal IgE mast cells

We report a female patient with adult onset of cow's milk protein allergy. For 1 year, she experienced repeated gastrointestinal symptoms and had a single exercise-induced anaphylactic reaction. In addition to positive skin tests and specific IgE to milk proteins and a positive challenge test, immunohistochemistry of the small intestine showed a marked increase of IgE-positive mast cells. This finding is highly specific and could provide an additional tool for diagnosing cow's milk protein allergy and possibly also other food allergies.

Food allergy in children

The diagnosis of hypersensitivity reactions to foods in infancy and childhood requires the use of clinical skills and laboratory diagnostic methods to identify suspect foods. Patients and parents occasionally may need to keep food/symptom diaries to explore the association of foods and adverse reaction. Skin testing or RAST may shorten the list of potential allergens because of their excellent negative predictive value. Except for obvious serious allergic reactions after ingestion of a single food, confirmation of the reaction may be ideally confirmed by a DBPCFC, especially if the reported symptoms are subjective in nature. Equivocal responses should be repeated. Although many in vitro and in vivo diagnostic methods have been developed to potentially improve the diagnosis of food allergy in children, no test has been able to predict the results of the DBPCFC with any greater accuracy than skin tests or RAST. The "perfect" test with excellent positive and negative predictive values has yet to be developed.