Association between farm exposure and atopy, according to the CD14 C-159T polymorphism

BACKGROUND: A higher exposure to bacterial compounds is purported to explain the lower prevalence of allergy in farm children, but responsiveness to bacterial compounds is modulated by genetic factors. OBJECTIVE: To assess whether the protective effect of farm exposure on atopy is influenced by a CD14 promoter functional polymorphism. METHODS: We administered a detailed questionnaire on farm exposure in childhood and genotyped the CD14 C-159T polymorphism in 2 French centers participating in the European Community Respiratory Health Survey (ECRHS)-II. RESULTS: Six hundred randomly selected young adults provided blood samples for IgE measurements and had CD14 C-159T genotyped. Exposure to a farming environment in early life was associated with a reduced risk of nasal allergies (odds ratio [OR], 0.54; 95% CI, 0.29-1.00) and atopic sensitization (OR, 0.47; 95% CI, 0.24-0.93) in adulthood. A lower risk of allergic rhinitis and atopy was also observed in carriers of the CD14-159TT genotype compared with -159CC subjects (OR, 0.52; 95% CI, 0.30-0.88; and OR, 0.54; 95% CI, 0.31-0.92, respectively). When farm exposure and CD14 C-159T were considered together, the risk of nasal allergies and atopy was the most reduced in the subjects who combined both an early-life exposure to a farming environment and the -159TT genotype (OR, 0.26; 95% CI, 0.07-0.94; and OR, 0.21; 95% CI, 0.05-0.93, respectively, vs nonexposed -159CC+CT subjects). The results were consistent in the 2 centers, supporting the validity of the results. CONCLUSION: A gene-by-environment interaction between CD14 C-159T and environmental exposure in childhood may modify the development of atopy. CLINICAL IMPLICATIONS: This polymorphism should be considered in interventions studies that use microbial stimuli to reduce sensitization.     

Farming environment and prevalence of atopy at age 31: prospective birth cohort study in Finland

Background Cross‐sectional studies have shown an association between the farming environment and a decreased risk of atopic sensitization, mainly related to contact with farm animals in the childhood. Objective Investigate the association of a farming environment, especially farm animal contact, during infancy, with atopic sensitization and allergic diseases at the age of 31. Methods In a prospective birth cohort study, 5509 subjects born in northern Finland in 1966 were followed up at the age of 31. Prenatal exposure to the farming environment was documented before or at birth. At age 31, information on health status and childhood exposure to pets was collected by a questionnaire and skin prick tests were performed. Results Being born to a family having farm animals decreased the risk of atopic sensitization [odds ratio (OR) 0.67; 95% confidence interval (CI) 0.56–0.80], atopic eczema ever (OR 0.77; 95% CI 0.66–0.91), doctor‐diagnosed asthma ever (OR 0.74; 95% CI 0.55–1.00), allergic rhinitis at age 31 (OR 0.87; 95% CI 0.73–1.03) and allergic conjunctivitis (OR 0.86; 95% CI 0.72–1.02) at age 31. There was a suggestion that the reduced risk of allergic sensitization was particularly evident among the subjects whose mothers worked with farm animals during pregnancy, and that the reduced risk of the above diseases by farm animal exposure was largely explained by the reduced risk of atopy. Having cats and dogs in childhood revealed similar associations as farm animals with atopic sensitization. Conclusion and Clinical Relevance Contact with farm animals in early childhood reduces the risk of atopic sensitization, doctor‐diagnosed asthma and allergic diseases at age 31. Cite this as: J. Lampi, D. Canoy, D. Jarvis, A.‐L. Hartikainen, L. Keski‐Nisula, M.‐R. Järvelin and J. Pekkanen, Clinical & Experimental Allergy, 2011 (41) 987–993.     

Serum IgE levels, atopy, and asthma in young adults: results from a longitudinal cohort study

To explore the natural history of asthma and its relation to allergic responses, we examined the relation between total serum IgE in early adulthood and a history of respiratory symptoms, airway hyperresponsiveness (AHR), and atopy during childhood. We studied 180 subjects aged 18–20 years who had been studied since the age of 8–10 years. We measured wheeze in the previous year by questionnaire, AHR by histamine inhalation test, atopy by skin prick tests, and serum IgE levels by immunoassay. Subjects with AHR in early adulthood had higher IgE levels (mean 257.0 IU/ml) than subjects with past AHR (mean 93.3 IU/ml) or with lifelong normal responsiveness (mean 67.6 lU/ml) ( P< 0.001). Subjects who had symptoms had higher IgE levels (mean 125.9 IU/ml) than those who were lifelong asymptomatic (mean 63.1 IU/ml) ( P< 0.001). Recent wheeze, AHR, and allergic sensitization all had a positive relation to serum IgE, but IgE was not more predictive of AHR than skin prick tests. The finding that young adults who are sensitized to common allergens are highly likely to have AHR even in the absence of symptoms is further evidence of the fundamental role of IgE-mediated responses in the natural history of AHR throughout childhood and into adulthood.     

Relationships of allergic sensitization, total immunoglobulin E and blood eosinophils to asthma severity in children of the EGEA Study

BACKGROUND: Although allergy is highly associated with childhood asthma, it is not well known if there is a relationship between the intensity of allergic sensitization and asthma severity. OBJECTIVE: The objectives of the study were to examine the relationships between several markers of allergy and asthma severity in asthmatic children included in the Epidemiological study on the Genetics and Environment of Asthma, bronchial hyper-responsiveness and atopy (EGEA). METHODS: The population comprised 216 asthmatic children below 16 years of age. Total IgE and blood eosinophil counts were measured and skin prick tests to 11 aeroallergens were performed. The intensity of the allergic sensitization was assessed by the number of positive skin prick tests and by skin weal sizes. Asthma severity was measured with four criteria: a clinical severity score, history of hospitalization for asthma, FEV1% predicted and inhaled steroid use in the last 12 months. RESULTS: Most of the children were sensitized to at least one aeroallergen (88.2%). Atopy was not related to the severity of asthma, except for a tendency for a more severe clinical score in non-atopic children. The type and intensity of the allergic sensitization were not associated with any criteria of asthma severity. Total IgE was significantly increased in children treated with inhaled corticosteroids and in children ever hospitalized for asthma (P-values 0.009 and 0.04, respectively). Eosinophil counts were not related to asthma severity. CONCLUSION: Our results suggest that severe childhood asthma may be related to a high level of total IgE but not to blood eosinophil counts. The lack of positive relationships between both atopy and the intensity of allergic sensitization with asthma severity supports the hypothesis of different risk factors being associated with asthma and with the severity of asthma.     

Geographical distribution of atopic rhinitis in the European Community Respiratory Health Survey I

Background: No large studies in adults has examined geographical variation in the prevalence of nasal allergy/allergic rhinitis in adults or considered the proportion of reported nasal symptoms on exposure to allergen attributable to atopy. The aim of this report was to describe the geographic distribution of subjects with nasal symptoms who are sensitized as determined by skin prick tests, using data from the European Community Respiratory Health Survey I. Methods: Information on the presence of nasal allergy, nasal symptoms on exposure to allergen and atopy using skin prick tests was collected from 15 394 adults aged 20–44 years living in 35 centres in 15 countries. Age sex standardized prevalence of symptoms and the attributable fraction of IgE sensitization for nasal symptoms on exposure to allergen were determined. Results: The age‐sex standardized prevalence of nasal allergy ranged from 11.8% in Oviedo (Spain) to 46.0% in Melbourne (Australia). The prevalence of atopic nasal allergy ranged from 4.6% in Oviedo to 31.8% in Melbourne (analysis limited on 12 566 subjects). The median attributable fraction for atopy on nasal symptoms on exposure ranged between 12.8% and 65.9% (median 27.2%). Conclusion: In the general population there is a wide variation in the prevalence of nasal allergy in young adults. Many subjects complaining from nasal symptoms on exposure to allergen are not atopic.     

Allergy markers in adults in relation to the timing of pet exposure: the EGEA study

BACKGROUND: Studies suggest that early childhood exposure to pets may protect from the development of atopy, but limited information is available on adults. The association of allergy markers in adulthood with current and childhood exposure to pets was studied considering retrospectively the window of exposure. METHODS: Immunoglobulin E (IgE), skin prick tests (SPT), eosinophils were related to exposure to pets in 187 adult asthmatic cases and 243 controls from the Epidemiological Study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy (EGEA) study. Analyses were redone after exclusion of subjects who removed pets or experienced symptoms to animals to take into account selection in that retrospective study. RESULTS: In asthmatic cases, current exposure to pets was unrelated to SPT positivity (+), whereas childhood exposure was significantly related to less SPT+ to any allergen, and to cat in particular, with an association restricted to those exposed before 2 years of age [OR = 0.30 (CI 0.12-0.76)]. Considering the relative timing of exposure in relation to asthma onset showed that the protective effect of exposure to pets occurs for pet exposure starting before asthma onset [OR for SPT+ = 0.19 (CI 0.08-0.48)]. CONCLUSION: Results support the hypothesis that exposure to pets in early life, and in particular before asthma onset, may protect against allergen sensitization in adulthood.     

Role of current and childhood exposure to cat and atopic sensitization. European Community Respiratory Health Survey.

BACKGROUND: Clinical and population studies have shown that exposure and sensitization to allergens derived from furred pets, particularly cats, represent an important risk factor of allergic respiratory disease and also a significant risk factor for asthma. OBJECTIVE: In the framework of the multicenter European Community Respiratory Health Survey an analysis of the association of current and childhood exposure to cat with atopic sensitization to cat was conducted. METHODS: This study included cross-sectional data from 35 centers representing 16 countries. Altogether, 18,097 subjects were included, of whom 13,509 (75%) provided a blood sample for the measurement of specific IgE. Exposure data and data for potential confounders were extracted from an interviewer-led questionnaire. RESULTS: The prevalence of sensitization to cat (serum specific IgE >0.35 kU/L) was 9%. Among those who did not report allergic symptoms in the presence of pets or house dust, those who owned cats were significantly more likely to be sensitized to cats than were those who did not (odds ratio [95% confidence interval] 1.57 [1.20-2.06]. Childhood exposure to pets including cats was associated with lower sensitization to cats in adulthood, particularly among those with a positive family history of atopy (odds ratio [95% confidence interval] 0.68 [0.51-0.93]. Positive correlations were found between the community prevalence of cat and the prevalences of sensitization to cat, respiratory symptoms, physician-diagnosed asthma, and current asthma medication. CONCLUSIONS: Current cat ownership represents a significant risk for sensitization to cat if cats are allowed indoors. Our results support the hypothesis that childhood exposure to pets, including cats, might modulate immunologic mechanisms and reduce sensitization to cat in adulthood. The significant correlation found between the community prevalence of cat ownership and community prevalence of specific sensitization to cat represents the first documentation of such a relationship.     

The protective role of country living on skin prick tests, immunoglobulin E and asthma in adults from the Epidemiological study on the Genetics and Environment of Asthma, bronchial hyper-responsiveness and atopy.

BACKGROUND: Farming environment and traditional lifestyle seem to protect from childhood allergy. OBJECTIVE: The aim is to analyse the relationships of living in the country to asthma, positive skin prick tests and IgE among adults considering various windows of exposure over the life-span. METHODS: The study concerns 805 adults drawn from the Epidemiological study on the Genetics and Environment of Asthma, bronchial hyper-responsiveness and atopy (EGEA) (asthmatic cases, non-asthmatic controls, and parents of cases with and without asthma). Ever living in the country concerned 55% of the subjects. Early (beginning < 1 years), childhood (beginning < or = 16 years), prolonged (duration > or = 10 years) and current life in the country were studied. RESULTS: The results based on the case control and family components of the study show that IgE levels were significantly lower in those who ever lived in the country and in particular in those who lived for > or = 10 years. Positive skin prick tests (SPT) were significantly less prevalent in those who ever lived in the country and in particular in those with childhood (< or = 16 years) exposure. These associations remained independent of age, sex, smoking or asthma with IgE levels of 64 vs. 88 IU/mL; P = 0.004 for those ever living in the country vs. others and odds ratio for SPT positivity of 0.72 (95% CI [0.53-0.98]). In the more specific group with traditional mode of heating in childhood (use of wood) associations were stronger. The association with asthma, studied in parents of asthmatic probands showed that fathers, but not mothers, of asthmatics were significantly less often asthmatic themselves in relation to country living. CONCLUSION: Country life protects from asthma and adulthood allergy. The protective effect is not restricted to exposure in early childhood.     

Prenatal exposure to household pets influences fetal immunoglobulin E production

Background Early life pet exposure may protect against allergic sensitization during childhood. Few studies have evaluated the effect of prenatal pet exposure on potential neonatal markers of allergic risk. Objective The aim of this study was to investigate whether maternal exposure to pets affects cord blood IgE levels in a population‐based, general risk, ethnically mixed birth cohort. Methods Pet keeping during pregnancy was ascertained from women residing in a defined area of Wayne County Michigan and recruited from five staff model obstetric clinics. Maternal venous blood was analysed for total and allergen‐specific IgE along with cord blood total IgE from 1049 infants. Results Compared with infants from households with no cats or dogs kept indoors during pregnancy, infants whose homes had either cats or dogs had significantly reduced mean cord IgE levels [0.34 IU/mL (95% CI 0.30–0.38) vs. 0.24 IU/mL (0.20–0.27), P=0.025]. Similar effects were apparent in cat‐only households [0.21 IU/mL (0.16–0.27), P=0.020] and dog‐only households [0.24 IU/mL (0.19–0.29), P=0.045]. There was no effect on results when excluding mothers who reported avoiding pets due to allergy‐related concerns. Conclusion Mothers with either cats or dogs in their home during pregnancy deliver children with lower cord blood IgE levels compared with mothers who do not live with these pets, supporting the hypothesis that pet exposure influences immune development in a manner that is protective for atopy and is operant even before birth.     

A new framework for the interpretation of IgE sensitization tests

IgE sensitization tests, such as skin prick testing and serum‐specific IgE, have been used to diagnose IgE‐mediated clinical allergy for many years. Their prime drawback is that they detect sensitization which is only loosely related to clinical allergy. Many patients therefore require provocation tests to make a definitive diagnosis; these are often expensive and potentially associated with severe reactions. The likelihood of clinical allergy can be semi‐quantified from an IgE sensitization test results. This relationship varies though according to the patients’ age, ethnicity, nature of the putative allergic reaction and coexisting clinical diseases such as eczema. The likelihood of clinical allergy can be more precisely estimated from an IgE sensitization test result, by taking into account the patient's presenting features (pretest probability). The presence of each of these patient‐specific factors may mean that a patient is more or less likely to have clinical allergy with a given test result (post‐test probability). We present two approaches to include pretest probabilities in the interpretation of results. These approaches are currently limited by a lack of data to allow us to derive pretest probabilities for diverse setting, regions and allergens. Also, cofactors, such as exercise, may be necessary for exposure to an allergen to result in an allergic reaction in specific IgE‐positive patients. The diagnosis of IgE‐mediated allergy is now being aided by the introduction of allergen component testing which may identify clinically relevant sensitization. Other approaches are in development with basophil activation testing being closest to clinical application.     

Early‐life antibiotic exposure increases the risk of developing allergic symptoms later in life: A meta‐analysis

This study systematically reviewed and quantified the relationship between exposure to antibiotics during the first 2 years of life and the risk of allergies/atopies including hay fever, eczema, food allergy, positive skin prick testing (SPT), or elevated allergen‐specific serum/plasma immunoglobulin (Ig) E levels later in life. PubMed and Web of Science databases were searched for observational studies published from January 1966 through November 11, 2015. Overall pooled estimates of the odds ratios (ORs) were obtained using fixed or random‐effects models. Early‐life exposure to antibiotics appears to be related to an increased risk of allergic symptoms of hay fever, eczema, and food allergy later in life. The summary OR for the risk of hay fever (22 studies) was 1.23, 95% confidence interval (CI):1.13‐1.34; I²: 77.0%. The summary OR for the risk of eczema (22 studies) was 1.26, 95% CI: 1.15‐1.37; I²: 74.2%, and the summary OR for food allergy (3 studies) was 1.42, 95% CI: 1.08‐1.87; I²: 80.8%. However, no association was found for antibiotics exposure early in life and objective atopy measurements including positive SPT or elevated allergen‐specific serum/plasma IgE levels.     

Food processing and occupational respiratory allergy‐ An EAACI position paper

Occupational exposure to foods is responsible for up to 25% of cases of occupational asthma and rhinitis. Animal and vegetable high‐molecular‐weight proteins present in aerosolized foods during food processing, additives, preservatives, antioxidants, and food contaminants are the main inhalant allergen sources. Most agents typically cause IgE‐mediated allergic reactions, causing a distinct form of food allergy (Class 3 food allergy). The allergenicity of a food protein, allergen exposure levels, and atopy are important risk factors. Diagnosis relies on a thorough medical and occupational history, functional assessment, assessment of sensitization, including component‐resolved diagnostics where appropriate, and in selected cases specific inhalation tests. Exposure assessment, including allergen determination, is a cornerstone for establishing preventive measures. Management includes allergen exposure avoidance or reduction (second best option), pharmacological treatment, assessment of impairment, and worker's compensation. Further studies are needed to identify and characterize major food allergens and define occupational exposure limits, evaluate the relative contribution of respiratory versus cutaneous sensitization to food antigens, evaluate the role of raw versus cooked food in influencing risk, and define the absolute or relative contraindication of patients with ingestion‐related food allergy, pollinosis, or oral allergy syndrome continuing to work with exposure to aerosolized food allergens.     

Defining childhood atopic phenotypes to investigate the association of atopic sensitization with allergic disease

AIMS: Although atopic sensitization is common in childhood, its relationship to clinical allergic disease remains incompletely understood. We therefore sought to explore this relationship by defining sensitization based atopic phenotypes. METHODS: Children were recruited at birth (n = 1456) and reviewed at 1, 2, 4 and 10 years. Skin prick testing (SPT) to common allergens was done at 4 (n = 980) and 10 years (n = 1036) with lung function (n = 981), bronchial challenge (n = 784) and serum IgE (n = 953) testing at 10. Atopic phenotypes were defined, by sensitization pattern, for children with SPT at both 4 and 10 years (n = 823). RESULTS: Of phenotyped children, 68.0% were never atopic, 4.3% early childhood atopic (only atopic at age 4), 16.5% chronic childhood atopics (at 4 and 10 years) and 11.2% delayed childhood atopics (only at 10). Never atopics showed small but identifiable prevalence of allergic diseases such as asthma, eczema and rhinitis. Amongst allergen-sensitized subjects, aeroallergen predominated over food sensitization throughout childhood. Chronic childhood atopics showed highest prevalence of lifetime plus persistent wheeze, eczema and rhinitis, increased prevalence of aeroallergen sensitization, some evidence of persistent food sensitization, significantly greater cord IgE than never atopics (P = 0.006), plus higher total IgE (P < 0.001) and bronchial hyper-responsiveness (P < 0.001) at 10 years than other phenotypes. CONCLUSION: A proportion of childhood eczema, rhinitis and asthma is nonatopic. The commonest childhood pattern of atopy is chronic sensitization, associated with early, persisting and clinically significant allergic disease. The currently accepted childhood 'Allergic March' may oversimplify the natural history of childhood atopy and allergic disease.     

Serum immunoglobulin A concentration in infancy,but not human milk immunoglobulin A,is associated with subsequent atopic manifestations in children and adolescents: a 20‐year prospective follow‐up study

Background Serum and secretory IgA concentrations have been suggested to be inversely associated with allergic symptoms in children. Furthermore, low maternal milk IgA concentration has been suggested to be associated with the development of cow's milk allergy. Objective Our aim was to explore whether the serum IgA concentrations in infancy and the IgA concentration of maternal milk predict atopic manifestations in childhood and up to age 20 years. Methods A cohort of 200 unselected full‐term newborns was prospectively followed up from birth to age 20 years with measurement of serum total IgA at ages 2 and 6 months. The mothers were encouraged to maintain exclusive breastfeeding for as long as possible. Total IgA concentration of maternal milk was measured at birth (colostrum, n=169) and at 2 (n=167) and 6 (n=119) months of lactation. The children were re‐assessed at ages 5, 11 and 20 years for the occurrence of allergic symptoms, with skin prick testing and measurement of serum IgE. Results Children and adolescents with respiratory allergic symptoms and sensitization had a higher serum IgA concentration at age 2 months than the non‐atopic subjects. Colostrum and breast milk IgA concentrations were not associated with the development of allergic symptoms in the recipient infant. However, maternal milk IgA concentration at 6 months of lactation was inversely associated with elevated serum total IgE and positive skin prick test to tree pollen in the offspring at age 20 years. Conclusions and Clinical Relevance Increased serum IgA concentration at age 2 months is associated with the development of subsequent allergic symptoms and sensitization in childhood and adolescence. Maternal milk IgA concentrations are not associated with subsequent allergic symptoms in the recipient infant. The present study provides novel information on the role of IgA in the development of respiratory allergy and sensitization. Cite this as: M. Pesonen, M. J. T. Kallio, M. A. Siimes, E. Savilahti and A. Ranki, Clinical & Experimental Allergy, 2011 (41) 688–696.     

Early endotoxin exposure and atopy development in infants: results of a birth cohort study

BACKGROUND: Exposure to endotoxin in childhood is currently discussed to protect from the development of allergic diseases. OBJECTIVE: To study the effect of early endotoxin exposure on incidence of atopic sensitization, atopic dermatitis and wheezing until the age of 2 years in infants with different risk status in terms of parental atopy. METHODS: Data of 1942 infants of an ongoing birth cohort study were analysed by logistic regression. Endotoxin was measured in settled dust of the mothers' mattresses at infants' age of 3 months. Data on allergic symptoms and physicians' diagnoses were gathered by questionnaire. Sensitization to common food and inhalant allergens was assessed by specific serum IgE. RESULTS: High endotoxin levels increased the risk of repeated wheeze [adjusted odds ratio (OR) for 4th exposure quartile (Q4) 1.52, 95% confidence interval (CI) 1.08-2.14], but were associated with neither sensitization to food allergens nor atopic dermatitis. Stratification by parental atopy showed that there was an association of endotoxin exposure with incidence of repeated wheeze as well as with sensitization to inhalant allergens (P for trend = 0.008 and 0.044, respectively) only in infants with parental atopy, with the highest risk in the 4th exposure quartile (repeated wheeze: ORQ4 1.77, 95% CI 1.14-2.73; sensitization to inhalant allergens: ORQ4 1.69, 95% CI 0.70-4.11). CONCLUSION: Early endotoxin exposure in terms of mattress dust endotoxin levels seemed to increase the risk of atopic reactions to inhalant allergens at the age of 2 years, especially in infants at risk due to parental atopy. Our data disagree with an early protective effect of endotoxin on atopy development until the age of 2 years.     

Elevated cord serum IgE increases the risk of aeroallergen sensitization without increasing respiratory allergic symptoms in early childhood

BACKGROUND: Increasing prevalence of allergic disorders has focused attention on primary prevention. There is a need to improve the accuracy of early-life predictors of atopy so that the at-risk population can be accurately defined and preventive measures instituted. OBJECTIVE: The predictive capacity of elevated cord IgE, with or without family history of atopy, to allergic symptoms and skin prick test (SPT) sensitization is evaluated in a birth cohort followed up prospectively for 4 years. METHODS: A birth cohort of 1456 consecutively born children was recruited in 1989. Data were collected on family history of atopy and cord serum total IgE (cord IgE) was measured. Of these, 1218 children were seen in the clinic at 4 years to determine the development of symptoms and signs of allergic disease and 981 were skin tested to a range of common food and aeroallergens. RESULTS: Of 1218 children reviewed at age 4 years, 218 (17.8%) had symptoms of respiratory allergy and, of those skin tested (n = 981), 192 (19.6%) reacted positively. Twice as many children with elevated cord IgE (>/= 0.5 kU/L) at birth became sensitized to aeroallergens by age 4 years (34.8% vs 17.3%, P < 0. 001). Positive predictive value (PPV) of elevated cord IgE for the development of aeroallergen sensitization was better than that of family history of atopy (34.8 vs 22.6%). Combining paternal atopy with elevated cord IgE substantially increased the predictive capacity (PPV 77.8%). Cord IgE levels did not correlate with clinical asthma or rhinitis at age 4 years and PPV for allergic respiratory symptoms remained poor at all cutoffs. CONCLUSION: Cord IgE is better than family history for predicting atopy as defined by allergen sensitization and this predictive value can be further increased by combining cord IgE with paternal atopy.     

Sensitization pattern of crustacean‐allergic individuals can indicate allergy to molluscs

This study investigated the sensitization pattern of crustacean‐allergic patients according to tolerance to molluscs. Thirty‐one patients with anaphylaxis to crustaceans (14 with mollusc allergy and 17 with mollusc tolerance) were studied using skin prick tests (SPTs), specific IgEs (sIgEs) and SDS‐PAGE immunoblotting. IgE‐reactive shrimp proteins were identified by proteomic analyses. Patients with mollusc allergy presented more frequently SPTs positive to molluscs and higher sIgE titres in response to both molluscs and crustaceans. Shrimp‐sIgE and rPen a1‐sIgE values of 1.57 kU_A/l and 4.38 kU_A/l, respectively, showed positive likelihood ratios of 4.3 and 10.9 for the identification of mollusc allergy. Patients with mollusc allergy reacted more frequently to tropomyosin in immunoblots than did patients without it (93% vs 35%, respectively, P = 0.004). Reactivity to proteins other than tropomyosin (n = 14) was not different between the two groups. Among patients with crustacean anaphylaxis, patients with mollusc allergy and mollusc tolerance show a different pattern of sensitization, something that may help identify them.     

Caesarean delivery and risk of atopy and allergic disesase: meta-analyses

Background Studies of delivery by caesarean section (c‐section) and the offspring's risk of allergic diseases are of current interest due to concerns about the increased use of c‐section in many countries. However, previous studies have reported inconsistent findings. Objective We investigated whether delivery by c‐section is associated with an increased risk of atopy and allergic disease by reviewing the literature, performing a meta‐analysis, and assessing publication bias. Methods We used a systematic literature search of MEDLINE (1966 to May 2007). Six common allergic outcomes were included: food allergy/food atopy, inhalant atopy, eczema/atopic dermatitis, allergic rhinitis, asthma, and hospitalization for asthma. For each outcome a meta‐analysis was performed, where a summary odds ratio (OR) was calculated taking into account heterogeneity between the study‐specific relative risks. Publication bias was assessed using the funnel plot method. Results We identified 26 studies on delivery by c‐section and one or more of the six allergic outcomes. C‐section was associated with an increased summary OR of food allergy/food atopy (OR 1.32, 95% CI 1.12–1.55; six studies), allergic rhinitis (OR 1.23, 95% CI 1.12–1.35; seven studies), asthma (OR 1.18, 95% CI 1.05–1.32; 13 studies), and hospitalization for asthma (OR 1.21, 95% CI 1.12–1.31; seven studies), whereas there was no association with inhalant atopy (OR 1.06, 95% CI 0.82–1.38; four studies) and eczema/atopic dermatitis (OR 1.03, 95% CI 0.98–1.09; six studies). Funnel plots indicated that the association with food allergy/food atopy could be difficult to interpret due to publication bias. For each significant association with an allergic outcome, only 1–4% of cases were attributable to c‐section. Conclusion Delivery by c‐section is associated with a moderate risk increase for allergic rhinitis, asthma, hospitalization for asthma, and perhaps food allergy/food atopy, but not with inhalant atopy or atopic dermatitis. The increased use of c‐section during the last decades is unlikely to have contributed much to the allergy epidemic observed during the same period.