Biochemical properties of aeroallergens: contributory factors in allergic sensitization?

Recent studies indicate that the majority of clinically important aeroallergens are biochemically active, A diverse range of properties have been demonstrated but most possess either enzymatic activity (principally hydrolytic), enzyme inhibitory activity, low molecular weight ligand transporting or regulatory properties. In addition, some allergens are glycosylated and/or are structurally similar to proteins which have evolved to function in the respiratory system per se . Little attention has been given to the possibility that the biochemical activity of an allergen or any post-translational modifications contribute to sensitization. In this review, mechanisms with the potential to influence immunogenicity are discussed including interaction with respiratory secretions, epithelial disruption, interactions with immunocompetent cells and receptor mediated endocytosis. Given that many aeroallergens are structurally and functionally similar to a variety of endogenous (e. g. lysosomal enzymes) and exogenous proteins (e. g. microbial enzymes and glycoproteins), particular attention has been directed to the latter. This process represents an important non-adaptive defence mechanism which has evolved to recognize and process such proteins and it is feasible that it plays a similar role in the processing of some allergens entering the respiratory system.     

Fish and shellfish allergy in children: Review of a persistent food allergy

The increased consumption of fish and shellfish has resulted in more frequent reports of adverse reactions to seafood, emphasizing the need for more specific diagnosis and treatment of this condition and exploring reasons for the persistence of this allergy. This review discusses interesting and new findings in the area of fish and shellfish allergy. New allergens and important potential cross‐reacting allergens have been identified within the fish family and between shellfish, arachnids, and insects. The diagnostic approach may require prick to‐prick tests using crude extracts of both raw and cooked forms of seafood for screening seafood sensitization before a food challenge or where food challenge is not feasible. Allergen‐specific immunotherapy can be important; mutated less allergenic seafood proteins have been developed for this purpose. The persistence of allergy because of seafood proteins’ resistance after rigorous treatment like cooking and extreme pH is well documented. Additionally, IgE antibodies from individuals with persistent allergy may be directed against different epitopes than those in patients with transient allergy. For a topic as important as this one, new areas of technological developments will likely have a significant impact, to provide more accurate methods of diagnosing useful information to patients about the likely course of their seafood allergy over the course of their childhood and beyond.     

Dermatite atopique et allergie : quels liens ?

Atopic dermatitis (AD) is a very common chronic inflammatory skin disease in childhood, often the first step in the atopic march. It seems justified to look for a food or a respiratory allergy, being worsening or responsible for the AD. At infant age, some clinical features are consistent with a food allergy: a severe AD, with an early onset, uncontrolled by topical corticosteroids, and a history of immediate-type reactions. As sensitization to food allergens is very common (positive skin prick-test, atopy patch-test or specific IgE), the role of food allergens in worsening AD is difficult to affirm. So, it could be necessary to ask the advice of an allergist, to avoid unnecessary elimination diets. At older age, exposure to aeroallergens cans worsen AD. Looking for an aeroallergen allergy can help to choose the specific immunotherapy, which clinical efficacy on AD seems interesting.     

Molecular biology and allergy: current status and future prospects

Techniques of molecular biology are now being applied to all fields of clinieal medicine. Molecular biology shows particular promise in the field of allergy. Already, cloning studies are defining the protein sequence of many allergens and allowing recombinant allergens to be synthesized. Soon these reeombinant allergens will be added to immunotherapy extracts so that extracts will contain standard amounts of clinically important allergens. Molecular biology may fundamentally change the practice of allergy. The receptors for IgE on mast cells and basophils have been cloned. Mechanisms of regulation of IgE are being elucidated. It will soon be possible to design recombinant molecules i) to specifically inhibit the synthesis of IgE, ii) to inhibit the binding of IgE to its receptor, and iii) to prevent the transmission of signals which result in the release of mediators. The allergist may soon be able to attack the underlying atopic diathesis in his or her patients, not just treat the allergic symptoms.     

The ImmunoCAP® Rapid Wheeze/Rhinitis Child test is useful in the initial allergy diagnosis of children with respiratory symptoms

Recurrent upper or lower respiratory symptoms, possibly allergy‐related, are very frequent in childhood. It is therefore important that physicians involved in the primary care of these children have an accurate initial diagnostic tool available. In this study, we investigated the value of an in vitro diagnostic device testing 10 common allergens, the ImmunoCAP^® Rapid Wheeze/Rhinitis Child, for the primary evaluation of allergy. Children with non‐infectious upper or lower respiratory symptoms possibly related to allergy were recruited in the primary health care setting of private practices of physician trained in immunology/allergology. The investigators carried out their usual diagnostic work‐up including IgE tests, and the ImmunoCAP^® Rapid test was performed with capillary whole blood in a blinded way to the investigator. The investigators’ conclusions on major triggering allergens were compared to the ImmunoCAP^® Rapid test results. In the whole patient population (n = 185), the sensitivity of the ImmunoCAP^® Rapid test for unveiling allergic disease was 92% (95% CI: 86–96%) and the specificity 97% (95% CI: 86–100%). Current guidelines for allergy diagnosis suggest screening children with recurrent, moderate/severe diseases for allergies. For children with asthma falling into these categories, sensitivity was 100% (95% CI: 88–100%) and specificity 100% (95% CI: 69–100%); for children with moderate and severe rhinitis sensitivity was 93% (95% CI: 86–97%) and the specificity 100% (95% CI: 79–100%). The ImmunoCAP^® Rapid test is an accurate test, in particular with regard to high specificity, for diagnosing allergy in children with recurrent respiratory diseases in primary care settings.     

High prevalence of aeroallergen sensitization among infants of atopic parents

OBJECTIVE: To present methodology to identify atopic parents and determine the prevalence of sensitization to 15 aeroallergens in their infant offspring. STUDY DESIGN: A birth cohort of infants was identified from birth records; an infant was enrolled if 1 of the parents reported allergy respiratory symptoms and had a positive skin prick test (SPT) to a common aeroallergen. At age 1 year, these infants were tested to the same aeroallergens. RESULTS: Of the 680 enrolled infants, 28.4% were SPT+ to 1 or more aeroallergens and/or food, and 18.0% were positive to 1 or more aeroallergens. By category of allergens, 9.7% were sensitized to pollens, 7.5% to molds, 4.3% to house dust mite and/or cockroach, and 3.4% to dog and/or cat. Of the infants who were positive to an aeroallergen, 65.7% remained positive at age 2 years. CONCLUSIONS: Infants born to atopic parents with percutaneous sensitization to aeroallergens are at increased risk for aeroallergen sensitization during infancy, which persists to age 2 years. These findings suggest that current clinical practices, which generally avoid skin testing before age 2 years, be reassessed in this population of high-risk children.     

儿童变态反应性疾病相关因素研究

目的通过分析儿童变态反应性疾病(食物过敏、过敏性鼻炎、过敏性哮喘、过敏性湿疹)的相关因素,明确主要危险因素,以利早期预防及干预治疗。方法对2004年1月～12月诊断为变态反应性疾病的276例患儿进行问卷调查及相关实验室检查;随机选择无变态反应性疾病史的266例其他疾病患儿为对照。结果延长母乳喂养时间组发生变态反应性疾病的危险性较小(P<0.005)。特应性体质、过敏性疾病家族史、RSV感染和细菌感染与变态反应性疾病的发生有关(P<0.005)。婴儿期主要是食物过敏,之后以吸入性过敏原过敏为主。多因素Logistic回归分析表明影响儿童变态反应性疾病的主要危险因素是:自身特应性体质、喂养方式、食物过敏原、吸入过敏原,其OR值分别为11.144、2.414、16.888、40.439。结论早期明确变态反应性疾病高危因素,针对危险因素进行规范化管理及采取相应治疗,将防止呼吸道变态反应性疾病的发生与发展。     

Specific fungal exposures, allergic sensitization, and rhinitis in infants

Indoor air quality has become increasingly important as we live in a society where the majority of our time is spent indoors. Specific attention has been drawn to airborne fungal spores as a factor affecting indoor air quality. This study targeted shortcomings of other studies by utilizing long-term air sampling and total fungal spore enumeration to determine associations between health outcomes and fungal spore concentrations. Infants (n = 144) were clinically evaluated and had skin prick tests (SPT) for 17 allergens. Airborne fungal spores were collected using a Button Personal Inhalable Sampler (SKC Inc.) for 48 h at a flow rate of 4 l/min. Sampling was conducted in the spring (March-May) or fall (August-October) in 2003-2004. Fungal spores were analyzed using microscopy-based total counting and identified to the genus/group level. Total spore and individual genus concentrations were analyzed for associations with rhinitis and positive SPT results. Overall, concentrations varied widely, between <2 and 2294 spores/m(3). While no relationship was observed between SPT(+) and total fungal counts, several significant associations were found when analysis was conducted on the various fungal genera and health outcomes. Positive associations were obtained between: Basidiospores and rhinitis (p < 0.01), Penicillium/Aspergillus and SPT(+) to any allergen (p < 0.01), and Alternaria and SPT(+) to any allergen (p < 0.01). Inverse associations were found between: Cladosporium and SPT(+) to any allergen (p < 0.05), and Cladosporium and SPT(+) to aeroallergens (p < 0.05). This study indicates that health outcome may vary by fungal genera; some fungal types may have sensitizing effects while others may have a beneficial role.     

Discrepancy between sensitization to inhaled allergens and respiratory symptoms in pediatric patients with type 1 diabetes mellitus

According to the ‘Th₁/Th₂ paradigm’, children with type 1 diabetes mellitus (T1DM) should have a lower risk of developing allergic sensitization and, because of the involvement of insulin in modulating airway inflammation, different frequency or severity in allergy‐related respiratory manifestations. This article aims at evaluating the frequency and type of allergic sensitization and its respiratory manifestation, asthma and/or rhinitis, in a group of pediatric patients with T1DM. Patients (112) with T1DM, 7.8–16.9 yr of age (63 males and 49 females) were evaluated. Skin prick test (SPT) reactivity to the most common classes of aeroallergens were performed and compared with data obtained in 709 school‐aged children. The frequency of sensitization was not different in the T1DM and in the control subjects (43.7% and 40.8%, respectively; p = 0.55), with similar proportions of individuals sensitized to one allergen (32.7% and 38.1%, respectively; p = 0.47). In both groups, sensitization to house dust mite allergens was the most frequently detected (69.4% and 65.4%, respectively; p = 0.59), with a higher proportions of individuals sensitized to Graminae (+Cynodon dactylon; p < 0.0001) and a lower, but weakly significant, proportion sensitized to Parietaria (p = 0.03) in the T1DM group, as compared with controls. No differences were found between T1DM and control groups in the proportion of individuals reporting rhinitis (26.8% and 29.2%; p = 0.60). However, comparing separately sensitized and non‐sensitized subjects, a lower proportion of rhinitis subjects was detected in the non‐sensitized T1DM patients, when compared with the non‐sensitized control subjects (p = 0.01). In addition, no differences were detected between T1DM and control groups in frequency of symptoms related to ‘lifetime asthma’, i.e., asthma episodes during life (14.3% and 16.5%, respectively: p = 0.55), also when sensitized and non‐sensitized subjects were evaluated separately (p = 0.12 and p = 1.00, respectively). However, no T1DM patient had ‘actual asthma’, i.e., asthma episodes in the last year, vs. 5.8% of the individuals in the control group (p = 0.009), the difference being mostly ascribed to sensitized subjects (p = 0.012). Finally, out of the 16 T1DM patients with ‘lifetime asthma’, 15 had mild intermittent disease and only one mild persistent disease. T1DM does not seem to play a downregulating role on the development of allergic sensitization to aeroallergens, but may lower the frequency or the severity of its clinical manifestations at respiratory level.     

Skin‐prick test findings in atopic asthmatic children: A follow‐up study from childhood to puberty

In a prospective cohort study we investigated the course of allergic sensitization from childhood to puberty in a group of children with atopic asthma. An attempt was made to correlate the findings with the persistence of asthma. A total of 150 children with atopic asthma established at 7 years of age were evaluated when 8–10 years of age. A battery of skin‐prick tests (SPTs) to common environmental allergens, a detailed clinical history for asthma severity classification, and spirometric analyses, were performed. In 127 of these children a re‐evaluation was performed at puberty. A variety of statistical methods were used to analyze the results regarding changes in skin test reactivity to individual aeroallergens and atopic index (degree of atopy), as well as to determine any correlation between these changes and the persistence of asthma in puberty. A wide spectrum of modification in skin reactivity to common environmental allergens was observed, including the complete loss of sensitization to some allergens or the development of a new one to others. Specifically, 34% of asthmatic children sensitive to Dermatophagoides pteronyssinus and 52.7% sensitive to cat lost their sensitivity in puberty, while only 7.5% and 11.1%, respectively, became sensitized (p = 0.03 and p = 0.001, respectively). In contrast, regarding pollen sensitivity, 30.2% and 24% of asthmatic children became sensitive in puberty to olive pollen and grasses mix, respectively, and only 11.7% and 12.5%, respectively, lost their sensitivity to these allergens (p = 0.04). No correlation was shown between the skin test reactivity changes to individual allergens and the persistence of asthma, but a significant correlation was found between atopic index to indoor allergens in childhood and the persistence of asthma at puberty (p = 0.04). Interestingly, multi‐sensitivity to allergens (≥ 4 allergens) in childhood was also found to correlate with the persistence of asthma at puberty [p = 0.05, odds ratio (OR) = 2.65, 95% confidence interval (CI) 1.2–7.2]. Our findings indicate that significant modification of skin reactivity to common environmental allergens in atopic children with asthma in puberty can occur. However, no association between these changes and the persistence of asthma could be demonstrated, although children with indoor allergic sensitization and multi‐reactivity were found to have a higher probability of maintaining their asthma in puberty.     

Development of specific immunoglobulin E in coughing toddlers: A medical records review of symptoms in general practice

The aim of this study was to study whether young children, originally immunoglobulin E (IgE) negative and who became sensitized to specific inhalation allergens, presented more frequently to their general practi‐tioner (GP) with other allergy‐ and asthma‐related symptoms than children who remained IgE negative. It was also investigated whether asthma was diagnosed more often in children who developed IgE to inhalant allergens. Coughing children, 1–5 years of age, visiting the participating GPs, were tested for IgE antibodies to mites, dogs, and cats by using radioallergosorbent testing (RAST). All IgE‐negative (RAST < 0.2 IU/ml) children were re‐tested after 2 years. The medical records of 162 children were reviewed on asthma‐ and allergy‐related symptoms and on prescribed medication. After 30 months, 27 of the 162 children (17%) had become IgE positive for one or more allergens. Most children (93%) had visited their GP for treatment of respiratory symptoms during this period. However, the children who had become IgE positive had visited their GP more often than the children who remained IgE negative. Differences in visits were seen for: shortness of breath (52% IgE‐positive vs. 19% IgE‐negative children, respectively), wheeze (37% vs. 17%), allergic rhinitis (33% vs. 16%), and pneumonia (22% vs. 8%), but not for coughing (89% vs. 88%). The IgE‐positive children were more frequently diagnosed by their GP as having asthma (48%) than were the IgE‐negative children (23%). In a multivariate analysis, indicators of becoming IgE positive were: a visit for shortness of breath (odds ratio [OR] = 6.9; 95% confidence interval [CI] = 2.1–23.1) and two or more visits for wheeze (OR = 6.0; 95% CI = 1.9–19.2), adjusted for breast‐feeding, age, and asthma or allergy in the family. The positive predictive value (PPV) of being IgE positive with a diagnosis of asthma was 90% (whereas the negative predictive value was 48.0%) for a child attending their GP for treatment of wheeze. For recurrent coughing (six or more visits) and shortness of breath, the PPVs were 73% and 71%, respectively. The development of sensitization to common inhalant allergens is associated with specific allergy and asthma‐related symptoms in young children. IgE‐positive children were more frequently diagnosed as having asthma by their GP. This implies that in general practice it is possible to detect children at high risk for developing allergic asthma early in life by their respiratory symptoms and by subsequent testing for specific IgE to inhalant allergens.     

Mite component–specific IgE repertoire and phenotypes of allergic disease in childhood: The tropical perspective

To cite this article: Kidon MI, Chin CW, Kang LW, Ching OT, Seng TY, Ning WK, Angus AC, Theng OS, Feng GY, Reginald K, Zhi BX, Shen SH & Tim CF. Mite component–specific IgE repertoire and phenotypes of allergic disease in childhood: The tropical perspective. Pediatr Allergy and Immunol 2011; 22 : 202–210. Sensitization to perennial aeroallergens correlates with the risk of persistent asthma (AS) in children. In tropical Singapore, multiple codominant species of mites abound in the indoor environment, and preferential species‐specific sensitization has been associated with different phenotypes of allergic disease. We investigated the pattern of mite component–specific IgE (mcsIgE) in children with different phenotypes of clinical allergic disease in an environment with multiple mite species exposure. A prospective evaluation of newly diagnosed patients with clinical diagnosis of allergic rhinitis (AR), atopic dermatitis (AD), or AS and sensitization to one or more aeroallergens were performed. Sera were tested for specific IgE against an extensive panel of Dermatophagoides pteronyssinus and Blomia tropicalis allergens. A total of 253 children were included, mean age 7.3 yr, 79% fulfilled criteria for AR, 46% AS, 71% AD, and 31% for all three. Sensitization to one or both mites was observed in 91% of children, 89% were sensitized to D. pteronyssinus, and 70% to B. tropicalis. The most common mite allergens recognized by these atopic children were Der p 1 (64%), Der p 2 (71%), Blo t 5 (45%), Blo t 7 (44%), and Blo t 21 (56%). Specific IgE responses to an increased number of distinct mite allergens correlated with the complexity of the allergic phenotype. In multivariate analysis, an increased risk for the multi‐systemic phenotype (AR + AS + AD) was associated with sensitization to an increased repertoire of mite components (three or more) (OR 4.3, 95% CI 2.1–8.8, p = 0.001) and a positive parental history of AS (OR 2.4, 95% CI 1.2–2.9, p = 0.013). A highly pleiomorphic IgE response to the prevalent indoor mites is associated with the presence of a multi‐systemic allergic phenotype in childhood in a tropical environment.     

Latex allergy and sensitization in children with spina bifida

BACKGROUND: The purpose of this study was to investigate the prevalence rate of latex sensitization and latex allergy among children with spina bifida and to evaluate risk factors for natural rubber latex hypersensitivity. METHODS: A total of 34 children between 2.5 and 17 years of age participated in the study. Participants completed a questionnaire and underwent skin prick tests with latex, common aeroallergens and food allergens as well as measurements of specific IgE to latex and food allergens (RAST CAP). RESULTS: The prevalence of latex sensitization and latex allergy was estimated to be 32.4 and 18.8%, respectively. The most common reported clinical manifestation of latex allergy was urticaria. Three out of six symptomatic patients reported anaphylactic reactions. CONCLUSION: We found that major risk factors for latex sensitization were atopy and a history of numerous operations.     

The role of dietary interventions in the prevention of IgE‐mediated food allergy in children

Over the last 30 years, the prevalence of food allergy has been on the rise and remains a disease that can have a significant impact on the quality of life of children and their families. There are several hypotheses that have been suggested to account for the increasing prevalence, but this review will focus on the impact that dietary factors have on food allergy development. In the past food allergy, prevalence has largely focused on allergen avoidance; however, there is increasing evidence from interventional studies that have shown that early introduction to potential food allergens may have a beneficial role in allergy prevention. This review aims to look at the evidence in support of early introduction of allergens into infant diets to prevent against the development of food allergy.     

Exhaled nitric oxide in asthmatic and non-asthmatic children: Influence of type of allergen sensitization and exposure to tobacco smoke

Asthmatic bronchial inflammation is associated with increased nitric oxide concentrations in exhaled air (eNO). Recent data suggest that this effect arises from atopy. Our aim in this study was to find out whether atopy and sensitization to particular allergens influences eNO levels. A total of 213 subjects (41 asthmatics and 172 controls) (96 boys and 117 girls, 7.3–14 years of age) were studied. Parents completed a questionnaire that sought information on their children's respiratory symptoms and exposure to tobacco smoke. Subjects underwent skin‐prick tests for the following common allergens: Dermatophagoides pteronyssinus (Dpt), cat fur, Aspergillus fumigatus, Alternaria tenuis, mixed grass, mixed tree pollen, Parietaria officinalis, egg, and cow's milk. eNO was collected in 1‐l mylar bags (exhaled pressure 10 cmH₂O, flow 58 ml/s) and analyzed by using chemiluminescence. Atopic and non‐atopic children without a history of chronic respiratory symptoms had a similar geometric mean eNO (atopics, n = 28, 11.2 p.p.b.; non‐atopics, n = 96, 10.0 p.p.b.; mean ratio 1.1, 95% confidence interval [CI]: 0.7–1.6). Conversely, atopic asthmatic subjects had significantly higher eNO values than non‐atopic asthmatic subjects (atopics, n = 25, 24.8 p.p.b.; non‐atopics, n = 16, 11.4 p.p.b.; mean ratio 2.2, 95% CI: 1.2–3.9, p= 0.000). In children with rhinitis alone (n = 15) and those with lower respiratory symptoms other than asthma (n = 33), eNO increased slightly, but not significantly, with atopy. eNO levels correlated significantly with Dpt wheal size (r = 0.51) as well with the wheal size for cat, mixed grass, and Parietaria officinalis (r = 0.30–0.29), and with the sum of all wheals (r = 0.47) (p= 0.000). Subjects sensitized only for Dpt (but not those subjects sensitized only for grass pollen or other allergens) showed significantly higher eNO levels than non‐atopic subjects (16.4 p.p.b. vs. 10.2 p.p.b., mean ratio 1.6, 95% CI: 1.1–2.3, p= 0.002). In asthmatic subjects, Dpt sensitization markedly increased eNO levels (Dpt‐sensitized subjects: 28.0 p.p.b.; Dpt‐unsensitized subjects: 12.2 p.p.b.; mean ratio 2.3, 95% CI: 1.5–3.5, p= 0.000). Non‐asthmatic Dpt‐sensitized subjects also had significantly higher eNO values than non‐asthmatic, non‐Dpt‐sensitized subjects (14.2 p.p.b. vs. 10.1 p.p.b.; mean ratio 1.4, 95% CI: 1.1–1.9, p= 0.008). No difference was found between eNO levels in asthmatic subjects and control subjects exposed or unexposed to tobacco smoke. In conclusion, eNO concentrations are high in atopic asthmatic children and particularly high in atopic asthmatics who are sensitized to house‐dust mite allergen.     

儿童变态反应性疾病过敏原3 504例调查分析

目的：了解儿童变态反应性疾病的过敏原状况,以便于有针对性的预防和治疗。方法：对3 504例各种变态反应性疾病患儿,采用UniCAP100系统检测血清fx5E（食物筛查试验）或Phadiatop（环境吸入性筛查试验）,及血清特异性IgE。结果：过敏性鼻炎、过敏性结膜炎、哮喘及丘疹性荨麻疹患儿的血清环境吸入性变应原阳性率明显高于食物性变应原,而过敏性紫癜及消化道疾病患儿的食物性变应原阳性率明显高于环境吸入性变应原。环境吸入性特异性IgE水平较高,屋尘、户尘螨、粉尘螨大部分达到6级,食物性特异性IgE水平较低,均在3级以下。结论：不同的儿童变态反应疾病的食物和环境吸入过敏原有显著差异,环境吸入性特异性IgE水平较食物性特异性IgE高。［中国当代儿科杂志,2010,12（9）：720-722］     

Feeding during the first months of life and prevention of allergy]

Allergy consists in the different manifestations resulting from immune reactions triggered by food or respiratory allergens. Both its frequency and severity are increasing. The easiest intervention process for allergy prevention is the reduction of the allergenic load which, for a major allergen such as peanuts, has to begin in utero. The primary prevention strategy relies first on the detection of at risk newborns, i.e. with allergic first degree relatives. In this targeted population, as well as for the general population, exclusive breastfeeding is recommended until the age of 6 months. The elimination from the mother's diet of major food allergens potentially transmitted via breast milk may be indicated on an individual basis, except for peanut, which is systematically retrieved. In the absence of breastfeeding, prevention consists in feeding at-risk newborns until the age of 6 months with a hypoallergenic formula, provided that its efficiency has been demonstrated by well-designed clinical trials. Soy based formulae are not recommended for allergy prevention. Complementary feeding should not be started before the age of 6 months. Introduction of egg and fish into the diet can be made after 6 months but the introduction of potent food allergens (kiwi, celery, crustaceans, seafood, nuts, especially tree nuts and peanuts) should be delayed after 1 year. This preventive policy seems partially efficacious on early manifestations of allergy but does not restrain the allergic march, especially in its respiratory manifestations. Probiotics, prebiotics as well as n-3 fatty polyunsaturated acids have not yet demonstrated any definitive protective effect.     

Epidemiology of atopy patch tests with food and inhalant allergens in an unselected population of children

Atopy patch test (APT) has been used as a diagnostic tool in patients with suspected food or inhalant allergy. This study assessed the prevalence of positive APT with food or inhalant allergens in an unselected population of schoolchildren. We also evaluated the link between positive APT reactions and skin‐prick tests (SPT) for food and inhalant allergens, circulating eosinophils and histamine skin reactivity. We studied an unselected population of 380 children aged 9 or 13 yr living in Rome, Italy. APTs were carried out with food (native or standardized) and inhalant allergens. All the children also underwent skin‐prick testing with five common inhalant and four food allergens. We also measured eosinophil cell counts and histamine skin reactivity. The prevalence of positive APT reactions for foods in unselected children ranged between 4% and 11% for hen’s egg, tomato, and wheat flour and was similar for both age groups studied. The prevalence of positive APT for milk was significantly lower in children aged 13 than in children aged 9 (p = 0.013). No concordance emerged between positive APT and SPT for foods. Conversely, APT and SPT for inhalant allergens yielded statistically significant concordance (p < 0.001). APT produces positive reactions for food or inhalant allergens in a significant number of subjects in the general population of schoolchildren. Age influences the prevalence of positive APTs with cow’s milk to some extent. Inhalant allergens probably induce a positive APT reaction through an immunoglobulin E‐linked process, while food allergens probably do not.     

Eosinophils and eosinophil cationic protein in children with and without sensitization to inhalant allergens

Eosinophil inflammation is a common feature of allergic disorders and particularly in allergic asthma interest has been paid to related markers. In a communitybased survey of 10-year-old children, the association of eosinophil count (EC) and serum eosinophil cationic protein (ECP) with allergic sensitization, clinical history and exposure to mite allergen was studied. Relying on the results of skin prick tests, the children were divided to three groups: (1) children showing no sensitization to one of the seven inhalant allergens (n=16); (2) children with sensitization to at least one of five non-mite allergens (n=16); and (3) children with sensitization to mite allergens (n-75). Clinical history of asthma and hay fever was ascertained using standardized questionnaires. EC in peripheral blood and serum ECP were measured on one single occasion. Prior to blood sampling, mite allergen exposure at home had been assessed by taking dust samples and measuring the mite antigen concentration by means of an enzyme immunoassay. Compared to group 1, higher ECs were obvious in group 2 (P=0.037) and in group 3 (P=0.0013). Regarding serum ECP, higher levels occurred in group 2 (P=0.0033) as well as in group 3 (P=0.0001) when comparing them to the reference group. Sensitized children with neither asthma, nor asthma-like symptoms, nor hay fever (n=28) did not have significantly lower ECs and serum ECP levels than those with hay fever (n=15;P=0.09,P=0.17) and those with asthma (n=22;P=0.69,P=0.64). Since mild asthmatics were in general included, our findings were limited with regard to clinical severity. Using multiple linear regression, EC occurs in positive association with mite allergen exposure at home (P=0.033) and with a history of asthma-like symptoms (P=0.02).Conclusion Our findings indicate that EC and serum ECP are confounded by the status of allergic sensitization. Therefore, value and limits of both parameters need further investigation before use in the management of allergic children can be recommended.