The development and prediction of atopy in high-risk children: follow-up at age seven years in a prospective randomized study of combined maternal and infant food allergen avoidance

Ketotic hypoglycemia in patients with allergic diseases

BACKGROUND

Ketotic hypoglycemia is the most common cause of recurrent hypoglycemia in early childhood but its etiology is poorly understood. Elimination diets have been used for the prevention or treatment of some allergic diseases; however, these diets entail a risk to the normal nutrition and growth of children. The present study investigated whether elimination diets are related to the occurrence of ketotic hypoglycemia.

METHODS

The prevalence of allergy treated with elimination diet therapy was retrospectively investigated in 18 patients with ketotic hypoglycemia seen in Yamaguchi University Hospital between January 1995 and September 1999. Data were gathered by reviewing the patients' medical charts.

RESULTS

Ten (55.6%) of 18 patients with ketotic hypoglycemia had allergic diseases. Six (60%) of the patients had been treated with strict elimination diets and the others were on incomplete elimination diets for the prevention of allergy. The ketotic hypoglycemia patients with allergic diseases had experienced fewer pre-existing infectious diseases than those without allergic diseases.

CONCLUSIONS

Patients with allergic diseases treated with elimination diets have a relatively high tendency towards developing ketotic hypoglycemia. They might have a lower capacity to tolerate fasting due to their excessive avoidance of many foods, even during periods when they are not undergoing strict elimination diets.

Clinical value and measurement of specific IgE

The diagnosis of human allergic diseases involves the combined use of a careful clinical history, physical examination, and in vitro and in vivo assay methods for the detection of IgE antibodies of defined allergen specificities. In vivo (skin testing) and in vitro (measurement of specific IgE in serum) techniques cannot be considered interchangeable, the former reflecting not only the presence of IgE but also mast cell integrity, vascular and neural responsiveness. Both techniques have similarities and differences, advantages and disadvantages. Recently introduced "second generation" immunoassays have continued to improve the analytical sensitivity and reproducibility thanks to automation and improved reagent quality. Quantitative assays may allow the use of specific clinical thresholds able to differentiate symptomatic from asymptomatic patients. False-negative and false-positive results should derive from lability of some major extracts, and from possible cross-reactivities, respectively. Characterization of allergens at a molecular and submolecular level and, where necessary, the use of recombinant allergens can reduce cross-reactions and further improve the quality of immunoassays.

Primary and secondary prevention of allergic airway disease

The incidence of atopic conditions is continuing to rise. The number of primary prevention cohorts is increasing and results are becoming available. There is a lack of true secondary prevention trials, however. This article reviews the results currently available from primary and secondary prevention studies.

Primary dietary prevention of food allergy

OBJECTIVE

To present research and clinical evidence on the use of primary dietary prevention in food allergy management.

DATA SOURCES

We conducted MEDLINE searches for pertinent articles published between January 1986 and October 2001 with use of the following keywords or phrases: prevention and diet and allergy, food allergy and prevention, and dietary prevention and food allergy or allergens. Also included are information and commentary reflecting the authors' cumulative clinical experience in an allergy unit of a city hospital.

RESULTS

We define as "proactive" those strategies centered on "success factors," such as the early postnatal environment, prolonged breast-feeding, and use of formula and probiotic supplementation, in contrast to earlier "prohibitionist" approaches to prevention of food allergy. These two approaches are not antagonistic and may even be synergistic. We introduce this distinction in light of epidemiologic evidence and out of concern about compliance and the quality of life for patients.

CONCLUSIONS

Inasmuch as nutritional and immune maturation are implicated, the prohibitionist measures that are most effective in primary prevention of food allergy are exclusive breast-feeding for at least 6 months (for lifelong immunity and other benefits), delayed (after the sixth month) introduction of solid foods, and on-indication use of "hypoallergenic" formulas. Whether proactive strategies can be contemplated remains a debatable issue. Evidence for and against the scientific use of probiotics as well as microbiologic, epidemiologic, and clinical data are discussed. Review of published epidemiologic studies and randomized clinical trials is essential before planning dietary intervention or prevention.

Therapeutic modalities for cow's milk allergy

OBJECTIVE

To discuss current therapeutic modalities for cow's milk allergy and its prevention.

DATA SOURCES AND STUDY SELECTION

The sources of data include original clinical studies carried out at Ste. Justine Hospital, as well as a systematic search of the published English and French language scientific literature restricted to human subjects using computerized searches (National Public Library of Medicine, Cochrane Database Systems Review) from 1997 to 2002. Search terms for article retrieval included food allergy, milk allergy, therapy, and prevention.

CONCLUSIONS

The therapy of food allergies depends upon an accurate diagnosis, which remains a challenge in non--IgE-mediated cases. Dietary exclusion remains the mainstay of therapy, with medications reserved for exceptional patients. Preliminary evidence suggests that pancreatic enzyme supplementation may be of benefit for cases with multiple food allergies and severe eczema. Hydrolysate formula use is currently recommended for dietary allergy prevention in infants at an increased risk when maternal milk is insufficient or unavailable. The use of partially hydrolyzed formulas to prevent allergic disorders, including atopic dermatitis, is supported by clinical studies, but cannot be used in the already sensitized, milk-allergic child. Probiotics show enormous potential in preventing food allergic disorders as well.

Overcoming childhood asthma disparities of the inner-city poor

Asthmatic children living in low-income families in United States inner city communities continue to have disproportionately high rates of hospitalizations, emergency department visits, disability, and death. Current research implicates a combination of environmental, biologic, and disease mismanagement factors that underlie these poor outcomes. Multifaceted studies are underway to better understand this inner-city path to severe asthma. Efforts to optimize interventions, to implement them broadly, and to sustain them are also underway on local and national levels. It is hoped that these efforts will limit the severe consequences of asthma, narrow disparities in outcomes, and substantially reduce medical expenditures for asthma.

Weaning of infants

The WHO 2001 global recommendation is a one size fits all approach to weaning, an approach which may not take sufficient account of the special needs of some infants and fails to allow for the different problems encountered in the industrialised nations compared with economically developing countries. For the healthy normal birth weight full term infant born in an industrialised country, current research supports the benefit of exclusive breast milk feeding until 4-6 months. Evidence of harm through introducing solid food to these infants earlier than this is weak. Infants should be managed individually according to their needs.

A dual long-term effect of breastfeeding on atopy in relation to heredity in children at 4 years of age

BACKGROUND

The long-term effect of early feeding on atopic sensitization is still unsolved. The aim of this study was to evaluate the long-term effect of breastfeeding on atopy in groups of 4-year-old children stratified by atopic heredity.

METHODS

We collected four groups of 4-year-old children from a birth cohort: two groups with differing backgrounds of atopic heredity, all exclusively breast-fed for at least 3 months; and two groups with differing atopic heredity, but all fed with cow's milk-based formula during their first weeks. The data were collected with a questionnaire, skin prick testing, and measurement of serum total and allergen-specific IgE levels.

RESULTS

Breastfeeding significantly decreased the risk of allergic rhino-conjunctivitis [odds ratio (OR) 0.41, 95% confidence interval (CI) 0.18-0.95] and sensitization to furred pets, as measured by skin prick results, in children with atopic heredity, whereas in children without atopic heredity, breastfeeding was related to an increased risk of symptomatic atopy (OR 2.57, 95% CI 1.16-5.70), and high serum IgE values. A significant interaction was found between heredity and breastfeeding.

CONCLUSIONS

The long-term effect of breastfeeding was dual: in children with atopic heredity, breastfeeding protected against atopy, whereas in children without atopic heredity, it increased the risk of atopy.

The use of mutually exclusive categories for atopic sensitization: a contrasting effect for family size on house dust mite sensitization compared with ryegrass sensitization

Our aim was to examine the relative importance of family size on sensitization to two different allergens: ryegrass and house dust mite (HDM), using a mutually exclusive classification for allergen-specific sensitization. An 8-year follow-up birth cohort study of children born between 1988-89 was conducted. The follow-up sample consisted of 498 children residing in Northern Tasmania in 1997 (84% of eligible). Outcome measures included skin prick test (SPT) reaction to nine aeroallergens and parental questionnaire. Family size was defined as sibling number in 1997. Children with a positive SPT to either Der p or Der f house dust mite but not ryegrass were classified as HDM-exclusive (n = 84). Children with a positive SPT to ryegrass but not HDM were classified as ryegrass-exclusive (n = 43). Family size was associated with reduced ryegrass-exclusive sensitization [AOR 0.57 (0.39, 0.84) per increase in sibling number] but not HDM-exclusive sensitization [AOR 0.97 (0.77,1.23)]. The difference in the family size effect on these sensitization outcomes was significant (p = 0.02). Similarly, family size tended to be associated with reduced asthma among ryegrass-exclusive sensitized children [AOR 0.45 (0.18,1.12)] but not HDM-exclusive sensitized children [(AOR 1.46(0.80-2.65)]. Large family size was strongly associated with reduced sensitization for ryegrass allergens but not HDM allergens using mutually exclusive sensitization categories. If this difference is confirmed in other studies, the contrasting effect of family size may reflect differences between these allergens with regard to level or timing of early life exposure, differences in allergen -specific potentiation for sensitization or unidentified confounding. The use of mutually exclusive categories for allergen sensitization will assist future work on child atopic disease.

[Prevention of asthma and allergic diseases in children]

Allergic diseases have become a major public health problem in industrialized countries, justifying the development of prevention programs. A review of the literature on allergens and atopic symptoms, age of primary sensitization and other factors associated with allergic diseases development is presented and is followed by a discussion on prevention measures. The most recent physiopathological and immunological data indicate that persistent asthma and allergic diseases in adults may be associated with events in early childhood. The parallel increase in autoimmune and allergic diseases has been correlated with regulatory mechanism defects, contradicting the previous theory that involved a predominantly Th1 or Th2 pathway. The primary prevention of asthma and allergic diseases thus appear to be somewhat utopian. Indeed based on recent results, the risk of developing allergies appears to be related to modern "clean" lyfestyles. Secondary prevention is probably necessary, possibly through specific immunotherapy. Tertiary prevention must also be considered. Passive smoking must be prevented as it can alter the development of the respiratory system and promote allergen sensitization. Randomized, controlled, prospective studies are needed to evaluate the efficacy of the preventive measures.

Study on the Prevention of Allergy in Children in Europe (SPACE): allergic sensitization at 1 year of age in a controlled trial of allergen avoidance from birth

Several studies have demonstrated that early intervention may modulate the natural course of atopic disease. The objective of this study was to prevent sensitization to house dust mite and food allergens, as well as development of atopic symptoms, during infancy. To achieve this we employed the combination of an educational package with the use of mite allergen-impermeable mattress encasings. A multi-center European, population-based, randomized controlled study of children at increased atopic risk [study on the prevention of Allergy in Children in Europe (SPACE)] was performed in five countries (Austria, Germany, Greece, Great Britain, Lithuania) and included three cohorts of schoolchildren, toddlers and newborns. We report on the newborn cohort. A total of 696 newborns were included in Austria, Great Britain and Germany. Inclusion criteria were a positive history of parental allergy and a positive skin-prick test or specific immunoglobulin E (IgE) of >or= 1.43 kU/l against at least one out of a panel of common aeroallergens in one or both parents. At 1 year of age the overall sensitization rate against the tested allergens [dust mite allergens: Dermatophagoides pteronyssinus and D. farinae (Der p and Der f, respectively)] and food allergens (egg, milk) in the prophylactic group was 6.21% vs. 10.67% in the control group. The prevalence of sensitization against Der p was 1.86% in the prophylactic group vs. 5% in the control group. In conclusion, we demonstrated, in a group of newborns at risk for atopic diseases, that the sensitization rate to a panel of aero- and food allergens could be effectively decreased through the use of impermeable mattress encasings and the implementation of preventive measures that were easy to perform.

Maternal dietary antigen avoidance during pregnancy and/or lactation for preventing or treating atopic disease in the child

BACKGROUND

Some breastfed infants with atopic eczema benefit from elimination of cow milk, egg, or other antigens from their mother's diet. Maternal dietary antigens are also known to cross the placenta.

OBJECTIVES

To assess the effects of prescribing an antigen avoidance diet during pregnancy and/or lactation on maternal and infant nutrition and on the prevention or treatment of atopic disease in the child.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (October 2002) and contacted researchers in the field.

SELECTION CRITERIA

All randomized or quasi-randomized comparisons of maternal dietary antigen avoidance prescribed to pregnant or lactating women. We excluded trials of multimodal interventions that included manipulation of the infant's diet other than breast milk or of nondietary aspects of the infant's environment.

DATA COLLECTION AND ANALYSIS

We extracted data from published reports, supplemented by additional information received from the trialists we contacted.

MAIN RESULTS

The evidence from 4 trials involving approximately 451 participants does not suggest a protective effect of maternal dietary antigen avoidance during pregnancy on the incidence of atopic eczema during the first 12 to 18 months of life. Data on allergic rhinitis/conjunctivitis and urticaria are limited to a single trial each and are insufficient to draw meaningful inferences. Longer-term atopic outcomes have not been reported. The restricted diet during pregnancy was associated with a slightly but statistically significantly lower mean gestational weight gain, a nonsignificantly higher risk of preterm birth, and a nonsignificant reduction in mean birthweight.The evidence from 3 trials involving approximately 210 participants suggests a protective effect of maternal antigen avoidance during lactation on the incidence and severity of atopic eczema during the first 12 to 18 months, but methodologic shortcomings argue for caution in interpretation.One crossover trial involving 17 lactating mothers of infants with established atopic eczema found that maternal dietary antigen avoidance was associated with a nonsignificant reduction in eczema severity.

REVIEWER'S CONCLUSIONS

Prescription of an antigen avoidance diet to a high-risk woman during pregnancy is unlikely to reduce substantially her child's risk of atopic diseases, and such a diet may adversely affect maternal and/or fetal nutrition. Prescription of an antigen avoidance diet to a high-risk woman during lactation may reduce her child's risk of developing atopic eczema, but better trials are needed. Dietary antigen avoidance by lactating mothers of infants with atopic eczema may reduce the severity of the eczema, but larger trials are needed.

Food allergy: what can be done to prevent progression to asthma?

OBJECTIVES

The primary objective of this review is to discuss risk factors for asthma development in food allergen-sensitized children. In the paper we discuss the possible measures to prevent progression to asthma by allergen and other adjuvant factor avoidance.

DATA SOURCES

A review from literature of articles on these topics was performed.

STUDY SELECTION

Relevant publications on asthma risk factors and implementation of protective factors were critically evaluated.

RESULTS

Children with familiar history of atopy and sensitization to food proteins in early infancy are at high risk of subsequent respiratory allergic diseases and require specific prevention. Because early allergic sensitization is a significant risk factor for later development of asthma, prevention of asthma by early allergen avoidance is mandatory in high-risk children. Adjuvant factors such as tobacco smoke and mold exposure may act as nonspecific triggers for the development of atopy. The role of protective factors such as infections in early life, breast-feeding, a "healthy" diet needs to be evaluated in prospective studies. Pharmacologic intervention with antihistamines led to significant reduction in incidence of asthma in high-risk children, but confirmatory longitudinal studies in large populations are necessary.

CONCLUSIONS

There is now accumulating evidence that preventing exposure to house-dust mite may significantly reduce the prevalence of childhood asthma. However, allergen avoidance can not be recommended as the only strategy. Avoidance of adjuvant factors and implementation of potential protective factors aimed to reduce the risk to progression to asthma need to be evaluated in prospective studies.

Early sensitization to house dust mite is a major risk factor for subsequent development of bronchial asthma in Japanese infants with atopic dermatitis: results of a 4-year followup study

BACKGROUND

Bronchial asthma (BA) often develops in children with atopic dermatitis (AD). Identification of factors that could predict the development of asthma in children with AD is useful for early intervention.

OBJECTIVE

We undertook a 4-year followup study to clarify the factors involved in the development of BA in infants with AD.

METHODS

We registered 169 infants with AD who were free of BA at registration and examined the prevalence and characteristics of the subsequent development of BA among these patients.

RESULTS

Among the patients followed for 4 years, approximately 45% experienced asthma-like respiratory symptoms, and 35% were diagnosed as asthmatic patients by pediatric allergologists. Patients who developed BA showed early appearance of house dust mite (HDM)-specific immunoglobulin E (IgE) and persistently high levels of food-specific IgE. Male sex, a positive family history of BA, and the appearance of HDM-specific IgE were identified as significant risk factors for the early development of BA, but the significance of these parameters decreased thereafter. A positive family history of AD, the outcome of skin lesions, and keeping furred pets were also identified as risk factors in a part of the followup period. Among the parameters examined, the early appearance of HDM-specific IgE was the most significant risk factor.

CONCLUSION

Appearance of HDM-specific IgE antibodies in early childhood, which seems to be mainly influenced by genetic factors, is a major risk factor for the subsequent development of BA in children with AD, but the influence decreases after longer followup.

[Allergic colitis: clinical and morphological aspects in infants with rectal bleeding]

BACKGROUND

Recent studies indicate the importance of eosinophilis infiltrated in the rectal mucous which jointly with the clinical features can serve to establish the diagnostic of allergic colitis.

AIM

To describe prospectively, the clinical features and morphological abnormalities of the rectal mucosa in patients with rectal bleeding and clinical diagnosis of cow's milk allergy.

METHODS

Clinical features of 20 infants under 6 months of age were described. Morphological findings in rectal mucosa were compared with control group, with suspicion of congenital megacolon.

RESULTS

The mean age of the patients was 97 +/- 47 days, rectal bleeding started before 120 days in 85% of them; 40% were breastfed, 60% cow's milk formula or both. The most striking morphological feature, in 18 patients, was eosinophilic infiltration in the rectal mucosa. There was a significant statistical difference when these values were compared with control group.

CONCLUSIONS

The increased number of eosinophils in the rectal mucosa represent the most important characteristic of allergic colitis, in patients under 6 months, with rectal bleeding, when breastfed, cow's milk formula or both.

High incidence of adverse reactions to egg challenge on first known exposure in young atopic dermatitis children: predictive value of skin prick test and radioallergosorbent test to egg proteins

BACKGROUND

Egg skin prick test (SPT) and/or radioallergosorbent test (RAST) positivity has been described in infants and children with a food allergy, or in infants at high risk of atopy who have never eaten eggs. Clinical reactions are also observed when some of these children or infants eat eggs for the first time.

OBJECTIVE AND METHOD

A prospective study was made of 107 atopic dermatitis (AD) children (66 boys, 41 girls) aged 1-19 months (median 5 months) who had never ingested egg, to compare the outcome of a first oral egg challenge and the results of albumen and yolk SPTs and RASTs.

RESULTS

The egg challenge (conducted at age 12-24 months: mean 16 months, median 15 months) was positive in 72/107 children (67.3%). The reactions were immediate or early (first 6 h) in 56/72 (77.8%). The most severe (all within the first 6 h) were one case of anaphylactic shock (1.4%), three cases of laryngeal oedema (4.1%) and one serious attack of asthma (1.4%). The skin weal diameter at and above which reactions always occurred was 5 mm for both albumen and yolk. They were, however, also observed in the complete absence of a weal. The outcome of the challenge was always positive when the specific IgEs (sIgE) for albumen and yolk were > 99 KU/L and > or = 17.5 KU/L, respectively. Here, too, reactions were noted even when sIgE levels were < 0.35 KU/L.

CONCLUSION

AD children who have never eaten eggs may be sensitized and display reactions at the first ingestion. The percentage of reactions in this series was by no means negligible. These findings were observed in children with mild as well as moderate-severe AD when first examined. SPT for albumen and yolk diameter > or = 5 mm, and sIgE for albumen > 99 KU/L and for yolk > or = 17.5 KU/L were 100% specific in predicting the outcome of the challenge. It may thus be concluded that children with AD whose SPT and/or RAST for albumen and/or yolk are equal to or higher than these cut-off values should not be subjected to the oral challenge when consideration is given to the introduction of egg in their diet. Even when these cut-offs are not reached, however, clinical reactions to the challenge cannot be ruled out a priori, and it should be preferably performed in a protected environment, such as a hospital.

Probiotics: on-going research on atopic individuals

The challenge for the modern health care system is to fight against the increasing prevalence of atopic disease. The introduction of scientifically composed probiotic functional foods for prophylactic or therapeutic purposes could be one solution. Probiotics are live microbial food supplements or components of bacteria which have beneficial effects on human health. Specific strains have been demonstrated to exert powerful anti-pathogenic, anti-inflammatory and anti-allergic effects. The hygiene hypothesis suggests that atopic disease may arise from a lack of counterbalancing microbial exposure at an early age. The initial compositional development of the gut microflora is considered a key determinant of the development of both the immune responder phenotype and normal gut barrier functions. The regulatory role of probiotics in human allergic disease was first emphasised in the demonstration of a suppressive effect on lymphocyte proliferation and interleukin-4 generation in vitro. Subsequently, a significant improvement in the clinical course of atopic eczema was reported in infants given a probiotic-supplemented diet. The potential of probiotics to reduce the risk of atopic disease has recently been demonstrated in a double-blind, placebo-controlled study: probiotics administered pre- and postnatally for 6 months to at-risk subjects reduced the prevalence of atopic eczema to half of that observed in infants receiving placebo. Ongoing research is directed towards the development of novel techniques to characterise the gut microflora. Future research will clarify the mechanisms to control specific physiological processes in the evolution of atopic disease in at-risk populations or in the management of allergic diseases.

Preventive measures and their effects. Results from cohort studies

The prevalence of asthma and atopic diseases continues to rise. Genetic factors alone cannot explain this rapid rise and the immunological mechanisms involved are insufficiently explained to allow direct intervention on a population-wide scale. Long-term observational birth cohort studies have provided data on which primary prevention studies are based. This review discusses the "who", "how", "when" and "what" of primary prevention and the experiences to date in prospective intervention cohort studies.

Food allergy

Food allergy encompasses a range of disorders that result from adverse immune responses to dietary antigens. This group of conditions includes acute, potentially fatal reactions, and a host of chronic diseases that mainly affect the skin and gastrointestinal tract. Tools for diagnosis and management have not changed much in the past two decades, and include the clinical history, physical examination, tests for specific IgE antibody to suspected foods, elimination diets, oral food challenges, and provision of medications such as epinephrine for emergency treatment. However, much research in the past few years has enhanced our understanding of the clinical, epidemiological, and immunological aspects of these disorders. In this review I will discuss these advances and incorporate them into an improved diagnostic and management scheme. Additionally, emergent diagnostic, treatment, and prevention strategies are reviewed.

Allergy after ingestion or inhalation of cereals involves similar allergens in different ages

BACKGROUND

Cereals are among the major foods that account for food hypersensitivity reactions. Salt-soluble proteins appear to be the most important allergens contributing to the asthmatic response. In contrast, very limited information is available regarding cereal allergens responsible for allergic reactions after ingestion of cereal proteins.

OBJECTIVE

The aim of this study was to evaluate the allergenic reactivity of ingested and inhaled cereal allergens in different ages, in order to investigate if the response to different allergens would depend on the sensitization route.

METHODS

We included 66 patients in three groups. Group 1: 40 children aged 3 to 6 months who suffered from diarrhoea, vomiting, eczema or weight loss after the introduction of cereal formula in their diet and in which a possibility of coeliac disease was discarded. Group 2: 18 adults with food allergy due to cereals tested by prick tests, specific IgE and food challenge. Group 3: eight patients previously diagnosed as having baker's asthma. Sera pool samples were collected from each group of patients and IgE immunoblotting was performed.

RESULTS

We found an important sensitization to cereal in the 40 children. The most important allergens were wheat followed by barley and rye. Among the adults with cereal allergy, sensitization to other allergens was common, especially to Lolium perenne (rye grass) pollen. Immunoblotting showed similar allergenic detection in the three groups.

CONCLUSION

Clinically significant reactivity to cereal may be observed in early life. Inhalation and ingestion routes causing cereal allergy seem to involve similar allergens. The diet control was more effective in children. The possibility of cereal allergy after the introduction of cereal formula during the lactation period should not be underestimated.

Clinical update on peanut allergy

BACKGROUND

Peanut allergy is common, potentially severe, and there has been a recent surge in clinical investigation of this important food allergen.

OBJECTIVE

To provide the reader with a clinically oriented update on peanut allergy.

DATA SOURCES

English language articles were selected from PubMed searches (search terms: peanut allergy, food allergy, anaphylaxis) and selected abstracts with a bias toward recent (3 years) studies judged to have immediate, practical clinical implications.

RESULTS

Peanut allergy is an increasing problem in western diets that include this food. Both genetic and environmental factors influences the expression of this allergy. The at-risk subject is an atopic individual, with heightened risk for those with atopic dermatitis and/or other food allergies. The allergy is long-lived for most, may increase slightly in severity over time, but approximately 20% of young children will develop tolerance. Parameters that may identify the subset likely to achieve tolerance have been identified. Several large studies have determined laboratory parameters (skin tests, peanut-specific serum immunoglobulin E concentrations) with excellent predictive value (>95%) to diagnose current clinical reactivity or tolerance, although oral food challenges are necessary for a definitive diagnosis. Numerous practical lessons concerning management (avoidance, treatment, and prevention) have been identified.

CONCLUSIONS

Recent studies provide the clinician with an armament of improved diagnostic and treatment modalities for peanut allergy. Studies are underway that are likely to provide more definitive therapies in the near future.

Cellular immune responses to ovalbumin and house dust mite in egg-allergic children

BACKGROUND

Although IgE-mediated food (egg) allergy is typically lost with age the underlying immune mechanisms are not understood, particularly in relation to the development of persistent IgE-mediated aeroallergen sensitivity.

METHODS

Lymphoproliferation and cytokine responses (IL-5, IL-10, IL-13 and IFN-gamma) to house dust mite (HDM) allergen and egg ovalbumin (OVA) were assessed using peripheral blood mononuclear cells (PBMC) from children aged 6 months to 5 years (n = 59) with acute IgE-mediated egg allergy (urticaria and angiedema or anaphylaxis), as confirmed by positive skin prick testing (SPT). Of these 46 had positive SPT on the day of blood collection and 13 had outgrown egg allergy (negative SPT and successful egg challenge). Where possible, responses were compared with previous data from nonallergic children of similar ages (n = 107).

RESULTS

Transient lymphoproliferative responses to OVA were seen in both egg-allergic and nonallergic children, but were more marked and more prolonged in egg-allergic children. Younger egg-allergic children (< 18 months) showed a mixed Th0 cytokine response to OVA, with readily detectable IFN-gamma, IL-5, IL-13 IL-10. Although IL-13 and IL-5 responses (OVA) correlated in younger egg-allergic children, there was a dissociation of these Th2 responses with age. Loss of clinical reactivity to egg was associated with almost complete loss of IL-5 responses and OVA-specific lymphoproliferation. Although IL-13 levels tended to be lower with age, this was not significant. Strong IFN-gamma and IL-10 responses to OVA persisted in older children after loss of OVA-specific lymphoproliferation. Lymphoproliferative responses to HDM also developed earlier in egg-allergic children compared with nonallergic children. Th1 (IFN-gamma) responses to HDM were largely below detection prior to 18 months of age, but increased significantly with age. In egg-allergic children Th2 (IL-5, IL-13) HDM responses also progressively increased with age. At 3 years of age almost all egg-allergic children had positive SPT to HDM and positive lymphoproliferative responses to HDM, with strong Th1 and Th2 (Th0) cytokine production.

CONCLUSIONS

IL-5 responses (rather than IL-13) responses most closely reflected clinical food allergy, with dissociation of IL-5 and IL-13 responses in older and egg-tolerant children. In this population, food and aeroallergen sensitivity was not associated with inability to produce IFN-gamma, but rather with mixed Th2 and Th1 (Th0) responses. Strong IL-10 and IFN-gamma responses where associated with the development of tolerance, suggesting persistent 'regulatory' populations of OVA-specific T cells, rather than clonal deletion of OVA responsive T-cells.

Food allergy

Allergic disease is a major contributor to illnesses and mortality worldwide. Food hypersensitivity is often the first phenomenon in the allergic march that includes gastroenteropathy, eczema, asthma and hay fever. Recent evidence indicates that prevention of food hypersensitivity in early life is associated with reduction in the incidence of eczema and asthma in later childhood. Strategies for prevention include exclusive breast feeding, restriction of mother's diet during lactation, hydrolyzed formula, delayed introduction of allergenic solid foods and reduced exposure to house dust mites and tobacco smoke. This is a highly cost-beneficial and cost-effective approach.

Which clinical subgroups within the spectrum of child asthma are attributable to atopy?

STUDY OBJECTIVES

The contribution of atopy to childhood asthma has been debated. We aimed to examine the relationship between atopy and asthma, taking into account differences in respiratory symptoms and disease severity.

DESIGN

A cross-sectional asthma survey involving the following: (1) a population sample of 758 (81% of eligible) school children aged 8 to 10 years from randomly selected schools in the Australian Capital Territory in 1999, and (2) a hospital-based sample of 78 (70% of eligible) children attending the hospital for asthma. Skin-prick test results to 10 common aeroallergens were available on 722 children and 77 children, respectively. Baseline spirometry was obtained on a subset of school children (n = 515, 78% of eligible).

RESULTS

The association between atopy and wheeze by wheeze frequency over the past year was as follows: no episodes (odds ratio [OR], 1.00 [reference]), 1 to 3 episodes (OR, 3.27; 95% confidence interval [CI], 2.15 to 4.97), 4 to 12 episodes (OR, 3.44; 95% CI, 1.75 to 6.75), and > 12 episodes (OR, 8.70; 95% CI, 3.07 to 24.55), with a higher population attributable fraction (PAF) for > 12 episodes (75%) than 1 to 3 episodes (49%). Atopy was moderately related to asthma ever (OR, 2.09; 95% CI, 1.52 to 2.85; PAF, 33%) but strongly related to 1999 hospital attendance for asthma (OR, 16.95; 95% CI, 6.76 to 42.48; PAF, 89%). Adjustment for child age, gas heater use, and maternal smoking near the child did not materially alter these findings.

CONCLUSIONS

The clinical features of frequent wheeze or hospital asthma attendance are largely attributable to atopy, but infrequent wheeze or a history of asthma ever are not. Atopic children are overrepresented in the severe range of the asthma spectrum.

Cow's milk protein avoidance and development of childhood wheeze in children with a family history of atopy

BACKGROUND

In infants with a family history of atopy, food allergen avoidance has been advocated as means of preventing the development of atopic disease when breast-feeding is not possible or supplemental feeding is needed. Most infant formulas are based on cow's milk protein. Alternative choices include soya based and hydrolysed cows milk formulas.

OBJECTIVES

To estimate the effect of dietary avoidance of cow's milk protein on the development of asthma or wheeze in children.

SEARCH STRATEGY

The Cochrane database was searched for eligible trials until February 2002. The full text papers of all abstracts identified as RCTs were obtained and reviewed independently by two reviewers.

SELECTION CRITERIA

Randomised controlled trials involving children with a family history of atopy in at least one first degree relative were considered if feeding with cow's milk based standard formula was compared to dietary avoidance of cow's milk protein using soya or other hypoallergenic formula during the initial four months of life or longer.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data independently. A priori defined subgroups were the types of hypoallergenic artificial feed and dietary restrictions on mother and/or child's diet.

MAIN RESULTS

Six trials used hydrolysed formula for at least 4 months in addition to dietary restrictions and in some cases dust-mite reduction measures. The risk of infants experiencing asthma or wheeze during the first year of life was reduced compared to standard cow's milk based formula (Relative Risk =0.40, 95% Confidence Intervals 0.19, 0.85). Feeding soya-based formula as opposed to standard cow's milk formula did not reduce the risk of having asthma or wheeze at any age.

REVIEWER'S CONCLUSIONS

Breast-milk should remain the feed of choice for all babies. In infants with at least one first degree relative with atopy, hydrolysed formula for a minimum of 4 months combined with dietary restrictions and environment measures may reduce the risk of developing asthma or wheeze in the first year of life. There is insufficient evidence to suggest that soya-based milk formula has any benefit.

Primary prevention of asthma

There has been a dramatic increase in the prevalence of asthma over the last quarter century, particularly in the industrialized world. Although our understanding of asthma continues to improve, there is no cure for the disease. Primary prevention of asthma is the focus of this review. Asthma is a disease with multiple gene-environment interactions. Candidate genes for asthma are considered, and potential interaction between one of those genes, CD14, and an environmental factor, endotoxin, is reviewed as it relates to the hygiene hypothesis. Environmental risk factors for asthma including allergens, pollutants, infectious factors, and dietary modifications are considered, particularly their potential for primary prevention of asthma. Ongoing cohort studies including the Canadian Allergy and Asthma Prevention Study, the Manchester Allergy and Asthma Study, the Children's Asthma Prevention Study from Australia, and the Prevention and Incidence of Asthma and Mite Allergy Study from the Netherlands are briefly reviewed. A more definitive understanding of genetic background and environmental triggers and their interactions is required before any specific approach to the primary prevention of asthma can be championed aggressively.

Study on the prevention of allergy in Children in Europe (SPACE): allergic sensitization in children at 1 year of age in a controlled trial of allergen avoidance from birth

Several studies have demonstrated that early intervention may modulate the natural course of atopic disease. Our objective was to prevent sensitization to house-dust mite and food allergens, as well as the development of atopic symptoms during infancy, by the combination of an educational package and the use of mite allergen-impermeable mattress encasings. A multicentre European, population-based, randomized, controlled study of children at increased atopic risk [Study on the Prevention of Allergy in Children in Europe (SPACE)] was performed in five countries (Austria, Germany, Greece, the UK, and Lithuania), and included three cohorts - schoolchildren, toddlers, and newborns. We report on the newborn cohort. A total of 696 newborns were included from Austria, the UK, and Germany. Inclusion criteria were: a positive history of parental allergy; and a positive skin-prick test or specific immunoglobulin E (IgE) (IgE > or = 1.43 kU/L) against at least one out of a panel of common aeroallergens in one or both parents. At 1 year of age, the overall sensitization rate against the tested allergens [dust-mite allergens: Dermatophagoides pteronyssinus and Dermatophagoides farinae (Der p and Der f)] and food allergens (egg, milk) in the prophylactic group was 6.21% vs. 10.67% in the control group. The prevalence of sensitization against Der p was 1.86% in the prophylactic group vs. 5% in the control group. In conclusion, we were able to demonstrate, in a group of newborns at risk for atopic diseases, that the sensitization rate to a panel of aero- and food allergens could be effectively decreased through the use of impermeable mattress encasings and the implementation of easy-to-perform preventive measures.

Epidemiology of food allergy/food intolerance in adults: associations with other manifestations of atopy

BACKGROUND

Food allergy and food intolerance (FA/FI) are believed to be frequent medical problems; however, information from epidemiologic studies in adults is scarce. The objective was to determine the frequency of FA/FI and allergic sensitization to food in a large adult sample. Furthermore, the associations between FA/FI and other outcomes of atopy were studied.

METHODS

Within a population-based, nested, case-control study, a standardized interview was performed to obtain detailed information on FA/FI and the history of atopic diseases. In addition, a skin prick test with 10 common food and nine aeroallergens was performed.

RESULTS

Overall, 20.8% of the 1537 studied subjects (50.4% female, age median 50 years) reported FA/FI (women 27.5%, men 14.0%; OR 2.35, CI 1.80-3.08). Nuts, fruits, and milk most frequently led to adverse effects, and the sites of manifestation were oral (42.9%), skin (28.7%), gastrointestinal (13.0%), systemic (3.2%), and multiple (12.2%). One-quarter of the subjects (25.1%) were sensitized to at least one food allergen in the prick test, with hazelnut (17.8%), celery (14.6%), and peanut (11.1%) accounting for most of the positive reactions. The corresponding frequency estimates for the representative study base (n=4178) were 15.5% for reported adverse reactions and 16.8% for allergic sensitization. Relevant concomitant sensitization to food and aeroallergens was observed. Food-allergic subjects (positive history and sensitization to corresponding allergen) suffered significantly more often from urticaria, asthma, atopic eczema, and especially hay fever (73.1%) than controls (3.0%). Furthermore, hay fever was treated significantly more often in subjects who suffered from concomitant food allergy.

CONCLUSIONS

FA/FI in adults is frequently reported and associated with other manifestations of atopy. Hay fever in conjunction with FA/FI tends to be clinically more severe since therapeutic needs are enhanced.

Development of allergy and IgE antibodies during the first five years of life in Estonian children

BACKGROUND

Epidemiological studies have demonstrated a low prevalence of allergic diseases and atopic sensitization among schoolchildren and young adults in the formerly socialist countries of Central and Eastern Europe as compared to Western Europe.

OBJECTIVE

The aim of our study was to prospectively investigate IgE responses to food and inhalant allergens and the development of allergy during early childhood in a population with a low prevalence of atopic disorders.

METHODS

In a population-based prospective study, 273 children were followed from birth through the first 5 years of life, recording manifestations of allergy by questionnaires and clinical examinations at 0.5, 1, 2 and 5 years (n = 213). Skin prick tests (SPT) were performed using natural foods (cow's milk, egg white) and commercial extracts of inhaled allergens (cat, dog, D. pteronyssinus, birch, timothy). In addition, serum IgE levels and circulating IgE antibodies against the seven allergens were determined.

RESULTS

The prevalence of allergic diseases at 5 years of life was 19%. Atopic dermatitis was the most common allergic disease at all ages. The point prevalence of positive skin prick tests was 7% at 0.5, 1 and 2 years of age, and 3% at 5 years. Circulating IgE antibodies against food allergens were common at all ages, i.e. 13, 23, 36 and 36%, respectively, at 0.5, 1, 2 and 5 years. The prevalence of circulating IgE antibodies to inhalant allergens increased from 1.5% at 0.5 years to 11% at 1, 19% at 2 and 47% at 5 years. The antibody levels were generally low, however. The value of positive SPT and the presence of IgE antibodies in the diagnosis of clinical allergy were low.

CONCLUSION

The results of this prospective study carried out in a previously socialist country with a low allergy prevalence among schoolchildren and young adults indicate that transient sensitization in early childhood is followed by a down-regulation of skin reactivity.

Early life risk factors for adult asthma: a birth cohort study of subjects at risk

BACKGROUND

Prediction of adult asthma is important, and early prevention strategies should be targeted at those most at risk. Identifying high-risk children at an early age, however, is currently difficult.

OBJECTIVE

We sought to determine those factors present in early life that predict an increased risk of adult asthma.

METHODS

A prospective cohort study of subjects at risk of asthma and atopy was undertaken in Poole, England. One hundred babies of atopic parents were recruited at birth. During the first 5 years of life, subjects were recalled annually, all respiratory events were reported, and skin prick tests and total serum IgE measurements were performed. At 11 and 22 years, bronchial hyperresponsiveness was also measured. Seventy-three subjects were followed up at 5 years, 67 at 11 years, and 63 at 22 years.

RESULTS

Twenty-three (37%) adult subjects reported wheezing within the previous 12 months. Fifteen (25%) of these subjects showed signs of bronchial hyperresponsiveness and were regarded as asthmatic. Wheezing before the age of 2 years occurred in 28% and was not significantly related to adult asthma (odds ratio, 0.3; 95% CI, 0.03-1.7; P = .19). A positive skin prick test response to hen's egg, cow's milk, or both in the first year was independently predictive of adult asthma (odds ratio, 10.7; 95% CI, 2.1-55.1; P = .001; sensitivity, 57%; specificity, 89%).

CONCLUSION

Prediction of adult asthma remains difficult. In this study of subjects at risk of atopy, skin sensitivity to hen's egg or cow's milk in the first year was predictive of adult asthma.

The pattern of atopic sensitization is associated with the development of asthma in childhood

BACKGROUND

Even though atopic sensitization has been shown to be strongly associated with childhood asthma, asthma eventually develops in only one third of atopic children.

OBJECTIVE

The aim of this study was to prospectively investigate the pattern of atopic sensitization typically associated with the development of asthma in childhood.

METHODS

The German Multicenter Allergy Study followed 1314 children from birth to the age of 7 years. Parental questionnaires on asthma and asthmatic symptoms were completed 6 times up to the age of 2 years and from then on yearly. Determination of specific IgE to 9 food and inhalant allergens was performed yearly, and at the age of 7 years, a bronchial histamine challenge was conducted.

RESULTS

Onset of atopic sensitization in atopic children with current asthma at the age of 7 years was significantly earlier than in atopic children without current asthma (39.4% before age 1 year vs 21.0%, P =.015). Early atopic sensitization without any sensitization to inhalant allergens at the age of 7 years conferred no increased risk for asthma at this age. Only those children sensitized to any allergen early in life and sensitized to inhalant allergens by the age of 7 years were at a significantly increased risk of being asthmatic at this age (odds ratio, 10.12; 95% CI, 3.81-26.88). However, even in this group of persistently sensitized children, the risk of being asthmatic at the age of 7 years was only increased if a positive parental history of asthma or atopy was present (odds ratio, 15.56; 95% CI, 5.78-41.83), with the effect being strongest for maternal asthma.

CONCLUSION

Our results indicate that an underlying factor pertaining to asthma and maternal transmission may determine both a certain pattern of sensitization and the expression of asthma.

Breast-feeding and the development of cows' milk protein allergy

Early feeding with cows' milk (CM) may cause cows' milk allergy (CMA). Breast milk contains many immune factors which compensate for the undeveloped defence mechanisms of the gut of the newborn infant. We studied the effect of supplementary CM feeding at the maternity hospital on the subsequent incidence of CMA, the effects of formula and breast feeding on the subsequent immunologic types of CMA, and the importance of immune factors present in colostrum in the immune responses of infants with CMA. In a cohort of 6209 infants, 824 were exclusively breast-fed and 87% required supplementary milk while in the maternity hospital: 1789 received CM formula, 1859 pasteurized human milk, and 1737 whey hydrolysate formula. The cumulative incidence of CMA, verified by a CM elimination-challenge test, was 2.4% in the CM, 1.7% in the pasteurized human milk and 1.5% in the whey hydrolysate group. Among these infants, exposure to CM at hospital and a positive atopic heredity increased the risk of CMA. Of the exclusively breast-fed infants, 2.1% had CMA. Risk factors for the development of IgE-mediated CMA were: exposure to CM at hospital, breast-feeding during the first 8 weeks at home either exclusively or combined with infrequent exposure to small amounts of CM and long breast-feeding. The content of transforming growth factor-beta1 (TGF-beta1) in colostrum from mothers of infants with IgE-mediated CMA was lower than from mothers of infants with non-IgE-mediated CMA. In infants with CMA, TGF-beta1 in colostrum negatively correlated with the result of skin prick test and the stimulation of peripheral blood mononuclear cells to CM, but positively with infants' IgA and IgG antibodies to CM proteins. Feeding of CM formula at maternity hospital increases the risk of CMA, but exclusive breast-feeding does not eliminate the risk. Prolonged breast-feeding exclusively or combined with infrequent exposure to small amounts of CM during the first 8 weeks induces the development of IgE-mediated CMA. Colostral TGF-beta1 may inhibit IgE- and cell mediated reactions and promote IgG-IgA antibody production to CM in infants prone to developing CMA.

Early introduction of cereals into children's diets as a risk-factor for grass pollen asthma

BACKGROUND

The prevalence of asthma has increased from the 1950s to the 1990s. The relationship between diet and asthma is an area of controversy that has never been fully evaluated. Attempts at dietary prevention of asthma have produced conflicting results. We have recently identified allergens from cereals that show cross-reactivity with proteins in grass pollen. An early intake of cereals in the diet during early life might cause IgE sensitization to cereals. It is not known whether such sensitization predisposes the development of allergy to pollen.

METHODS

To test this hypothesis, a cross-sectional study and an observational case-control analysis of reviewed data were carried out on 16381 patients who had been admitted to our Allergy Unit between 1989 and 1999. All the patients underwent allergy tests to identify asthma risk-factors. All information in our data base was analysed using the SPSS computer system.

RESULTS

There has been an increase of 7.8% in incidences of allergic asthma and a 7.3% increase in asthma due to grass pollen in the last decade. Grass-pollen asthma was associated with sensitization to cereals. The early introduction of cereals in the diet of children was found to be a risk factor for grass-pollen asthma (OR = 5.95; 95% CI 3.89-9.10).

CONCLUSIONS

These findings document the progression of allergic asthma during a decade in a large sample of people who were influenced by similar environmental conditions and studied with the same diagnostic methods. This study represents the largest database of patients in which a common food is shown to be a risk factor for asthma.

The childhood asthma prevention study (CAPS): design and research protocol of a randomized trial for the primary prevention of asthma

The Childhood Asthma Prevention Study is a randomized controlled trial to measure whether the incidence of atopy and asthma can be reduced by house dust mite allergen reduction, a diet supplemented with omega-3 fatty acids, or a combination of both interventions. Six hundred and sixteen pregnant women whose unborn children were at high risk of developing asthma because of a family history were randomized prenatally. Study groups are as follows: Group A (placebo diet intervention, no house dust mite reduction), Group B (placebo diet intervention, active house dust mite reduction), Group C (active diet intervention, no house dust mite reduction), and Group D (active diet intervention, active house dust mite reduction). The house dust mite reduction intervention comprises use of physical and chemical methods to reduce allergen contact. The dietary intervention comprises use of a daily oil supplement from 6 months or at onset of bottle-feeding, and use of margarine and cooking oils based on sunflower or canola oils to increase omega-3 dietary intake. Data is collected quarterly until the infant is 1 year old and then half yearly until age 5 years. Questionnaires are used to collect respiratory illness history and information about diet and home environment. Dust is collected from the child's bed and bedroom and playroom floors. Blinded assessments are conducted at 18 months, 3 years, and 5 years. Skin prick tests to common allergens, blood tests, and detailed illness, medication use, and vaccination histories are collected. Primary outcomes will be the development of allergic sensitization and the presence and severity of asthma. This study is designed to measure the effectiveness of allergen reduction and dietary supplementation, both separately and in combination, for the primary prevention of atopy and asthma. The results of this study may have important implications for public health policies to reduce the incidence of childhood asthma. Control Clin Trials 2001;22:333-354