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PubMed2002

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.

Asthma↗
PubMed2006

Home exposures, parental atopy, and occurrence of asthma symptoms in adulthood in southern Taiwan.

OBJECTIVE: Parental atopy and environmental exposures at home have been recognized risk factors for adulthood asthma. However, the relative contributions of specific risk factors and the overall contributions of heredity or home exposure remain unexplored. The purpose of this study was to identify predictors and estimate the population attributable risk (PAR) of each exposure for typical asthma symptoms among 26- to 50-year-old Taiwanese. We also investigated whether an interactive effect existed between parental atopy and home exposures on the occurrence of asthma symptoms in adulthood. DESIGN: A cross-sectional study with retrospective components. SETTING: Elementary and middle schools in Southern Taiwan. SUBJECTS: Between March and October 2004, we conducted a cross-sectional survey among schoolchildren's parents from 94 elementary and middle schools in Southern Taiwan. The main outcome measure was typical asthma-like symptoms occurring within the preceding 5 years. Information on hereditary and home exposures was collected by using a self-administered questionnaire. RESULTS: After excluding unqualified questionnaires, data from 24,784 subjects were left for analysis. New-onset asthma was reported for 0.83% of male (n = 80 of 9,662) and 1.36% of female subjects (n = 206 of 15,122). Besides parental atopic factors, environmental tobacco smoke or pet avoidance and visible mold on walls at home were independently associated with the occurrence of asthma symptoms. Mutually adjusted models produced statistically significant associations between any home exposure (odds ratio [OR], 1.80; 95% confidence interval [CI], 1.08 to 3.23; PAR, 28.04%), parental atopy (OR, 4.47; 95% CI, 3.47 to 5.75; PAR, 31.38%), and new-onset asthma. However, there was no interaction between parental atopy and home exposures. CONCLUSIONS: Home exposures and parental atopy both increased the risks of new-onset asthma in adulthood but did not show an interactive effect. These two exposure categories approximately contributed equally to the adulthood asthma.

Adult↗
PubMed1991

Atopy and primary lung cancer. Histology and sex distribution.

Atopy, defined as the ability to develop IgE antibodies to commonly encountered allergens under conditions of normal exposure, has an inherited component with pleiotropic effects. An inverse relationship between the occurrence of atopy, allergy-related diseases, and cancers at specific sites has been reported. The familial association of primary lung cancer is most evident among women, nonsmokers, and those with adenocarcinomas. In order to determine whether the relationship between a lower prevalence of atopy among patients with lung cancer compared to control subjects was consistent between histologic cell types, we used seven common allergens to allergy prick skin test 209 community control subjects (46 women), 109 cases with primary squamous cell carcinoma of the lung (25 women), and 67 patients with primary adenocarcinomas of the lung (23 women). We have confirmed earlier reports of an inverse relationship between atopy and lung cancer risk. In analyses focusing on sex and histologic cell type, we found that women with adenocarcinomas were an exception and were as likely to be atopic as control subjects. The evidence does not support a protective role for atopy among these women.

Adenocarcinoma↗
PubMed2005

Severity of respiratory syncytial virus bronchiolitis is affected by cigarette smoke exposure and atopy.

OBJECTIVE: Respiratory syncytial virus (RSV) bronchiolitis is a common cause of hospitalizations in children and has been increasingly identified as a risk factor in the development of asthma. Little is known about what determines the severity of RSV bronchiolitis, which may be helpful in the initial assessment of these children. DESIGN: We evaluated a variety of environmental and host factors that may contribute to the severity of RSV bronchiolitis in the RSV Bronchiolitis in Early Life prospective cohort study. Severity of bronchiolitis was based on the quantization of lowest O(2) saturation and the length of stay. These factors included the child's and family's demographics, presence of household allergens (dust mite, cat, dog, and cockroach), peripheral blood eosinophil count, immunoglobulin E level, infant feeding, prior illnesses, exposure to intrauterine and postnatal cigarette smoke, and family history of atopy. PATIENTS: We prospectively enrolled 206 hospitalized infants, all under 12 months old (4.0 +/- 3.3 months old), with their first episode of severe RSV bronchiolitis (mean O(2) saturation: 91.6 +/- 7.3%; length of stay: 2.5 +/- 2.5 days; presence of radiographic opacities: 75%). Patients were excluded for a variety of reasons including previous wheezing, regular use of bronchodilator or antiinflammatory medications, any preexisting lung disease including asthma, chronic lung disease of prematurity/bronchopulmonary dysplasia, or cystic fibrosis; gastroesophageal reflux disease on medical therapy; or congenital anomalies of the chest or lung. RESULTS: Age was found to be a significant factor in the severity of infection. The younger an infant was, the more severe the infection tended to be as measured by the lowest oxygen (O(2)) saturation. We also found that infants exposed to postnatal cigarette smoke from the mother had a lower O(2) saturation than those not exposed. However, there was no significant difference in RSV bronchiolitis severity between infants exposed only to intrauterine smoke and those infants never exposed to cigarette smoke. Infants with a family history of atopy, especially a maternal history of asthma or hay fever, had a higher O(2) saturation. Although a history of maternal atopy seemed to be protective, there was no association between allergens and bronchiolitis severity, although 25% of households had elevated allergen levels. Black infants demonstrated less severe RSV bronchiolitis than their white counterparts. Multivariate analysis revealed age, race, maternal atopy, and smoking to be associated with severity of RSV bronchiolitis. CONCLUSION: The severity of RSV bronchiolitis early in life seems modified by postnatal maternal cigarette smoke exposure and atopy and age of the infant, not by levels of allergens in the home environment.

Age Factors↗
PubMed2004

The relation of breastfeeding and body mass index to asthma and atopy in children: a prospective cohort study to age 6 years.

OBJECTIVES: We investigated the relationship between breastfeeding, asthma and atopy, and child body mass index (BMI). METHODS: From a prospective birth cohort (n = 2860) in Perth, Western Australia, 2195 children were followed up to age 6 years. Asthma was defined as doctor-diagnosed asthma and wheeze in the last year, and atopy was determined by skin prick test of 1596 children. Breastfeeding, BMI, asthma, and atopy were regressed allowing for confounders and the propensity score for overweight. RESULTS: Using fractional polynomials, we found no association between breastfeeding and overweight. Less exclusive breastfeeding was associated with increased asthma and atopy, and BMI increased with asthma. CONCLUSIONS: Less exclusive breastfeeding leads to increases in child asthma and atopy and a higher BMI is a risk factor for asthma.

Asthma↗
PubMed2006

Japanese cedar pollen as an exacerbation factor in atopic dermatitis: results of atopy patch testing and histological examination.

Atopy patch testing with Japanese cedar pollen extract has been used to investigate patients with atopic dermatitis whose condition is exacerbated by contact with Japanese cedar pollen. Comparative atopy patch testing, scratch tests, and assays for total IgE and specific IgE were performed in 74 patients with atopic dermatitis, 5 patients with Japanese cedar pollinosis and 15 control subjects. A skin biopsy was performed on any sites that were positive to Japanese cedar pollen patch test. The results after 48 h of atopy patch testing were compared with the patient's history, skin scratch test and specific IgE. Twenty-two of the 74 patients (30%) had a history of exacerbation every spring after contact with Japanese cedar. Of these patients 68% showed a positive reaction to Japanese cedar pollen extract, as did 21% of patients with atopic dermatitis without a history of exacerbation by Japanese cedar pollen, 20% of patients with Japanese cedar pollinosis without eruption and 7% of control subjects. A histological examination revealed eczematous changes and infiltration of lymphocytes and eosinophils in atopy patch testing positive sites. In conclusion, atopy patch testing with Japanese cedar pollen extract is a useful method for investigating trigger factors for eczematous skin lesions in a subgroup of patients with atopic dermatitis.

Adult↗
PubMed1993

Irritant reactivity is a better risk marker for nickel sensitization than atopy.

In order to optimize patch test strategies and counselling in occupational dermatology, it is important to identify risk markers of contact sensitization. Since nickel is the most frequent contact allergen in European countries, we studied the potential of the irritant response to sodium lauryl sulfate (SLS) to predict nickel sensitization. In 100 patients subsequently tested in our patch test clinic with the standard patch test series of the German Contact Dermatitis Group (DKG), the atopy score as described by Diepgen et al. was determined and an SLS patch test was performed. Relative transepidermal water loss (TEWL), expressed as the ratio between the TEWL of the SLS-irritated and the control site, atopy score, age and sex were tested by logistic regression analysis for their association with patch test-proven nickel sensitization. Age, sex and relative TEWL were found to be significant predictors of nickel sensitization, whereas the atopy score was not. Patients with nickel sensitization were significantly younger (mean age 35.0 +/- 4.1 versus 46.2 +/- 2.1 years), more frequently of female gender (28.6% versus 3.9%) and had a significantly higher relative TEWL following SLS exposure (471.0 +/- 40.8% versus 344.0 +/- 16.2%). The mean atopy score of nickel-sensitized patients was slightly higher than that of patients not sensitized (6.0 +/- 1.3 versus 5.3 +/- 0.5), but the difference was not significant. In previous studies on larger patient samples, atopy was found to be a predictor of nickel allergy. This discrepancy may be explained by the smaller statistical power of our study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Results of intradermal tests in horses without atopy and horses with chronic obstructive pulmonary disease.

OBJECTIVE: To compare results of intradermal tests (IDT), conducted using environmental allergens, in horses without atopy and horses with chronic obstructive pulmonary disease (COPD). ANIMALS: 38 horses (22 horses without atopy and 16 horses with COPD). PROCEDURE: All horses were examined (physical examination, hematologic examination, serum biochemical analyses, examination of bronchoalveolar lavage fluid). An IDT was conducted, using a full panel of 73 allergens consisting of grasses, weeds, trees, molds, and insects. Results of the IDT were evaluated 30 minutes and 4, 6, and 24 hours after injection of allergens. Horses without atopy were euthanatized, and gross and histologic changes of lung parenchyma were assessed. RESULTS: Horses without atopy had a greater number of positive immediate and late-phase reactions than did horses with COPD. Horses with COPD did not have a significantly greater number of positive reactions than horses without atopy at any time period for any allergen group (grasses, weeds, trees, molds, and insects). CONCLUSIONS AND CLINICAL RELEVANCE: Positive results of IDT document allergen-specific hypersensitivity but do not necessarily distinguish clinically relevant reactions from subclinical reactivity in horses with COPD. Interpreting the clinical relevance of results of IDT requires a thorough knowledge of the medical history, physical examination findings, and environment of each animal.

Allergens↗
PubMed2000

Daycare attendance, asthma and atopy.

The objective of this article is to review studies that have examined the relation of daycare to asthma and atopy. In order to identify studies for inclusion, abstracts of all studies referenced in Medline from January 1966 to January 2000 and in BIBSYS were searched and extracted if they included 'asthma' or 'atopy' combined with words such as 'daycare', 'nursery' or 'kindergarten'. Eight studies fulfilled the criteria of inclusion. The outcomes were asthma, skin prick test (SPT) reactivity, a positive radioallergosorbent test (RAST), hay fever, and eczema. Daycare attendance was positively associated with asthma in five of six studies including asthma. In three of these studies there was no statistically significant association between daycare and asthma. Early start in daycare protected against later asthma in one study. There was a weak, but not a statistically significant positive relation between daycare and atopy in two of three studies when SPT reactivity was used as the outcome. In children of small families early start in daycare protected against atopy. The quality of the studies varies, and they are not directly comparable. The relation between daycare attendance and asthma and atopy is unclear, and further studies designed to answer this specific research question are needed.

Asthma↗
PubMed1999

Signal transduction via the interleukin-4 receptor and its correlation with atopy.

IL-4 and IL-13 are unique cytokines, in that they induce IgE synthesis in B cells and TH2 type differentiation in T cells. Both cytokines exert their biological activities by binding to their functional receptors on target cells. These receptors are thought to be composed as heterodimers, both having the IL-4R alpha chain (IL-4Ralpha) as a component. Among the signal-transducing molecules of IL-4 and IL-13, Stat6, which is activated by these cytokines and recruits to IL-4Ralpha, is essential for the biological activities of these cytokines. Atopy is an inherited tendency, underlying asthma, rhinitis, and eczema, and generating high non-specific IgE and/or high specific IgE against common antigens. Based on information on the molecular mechanism of the signal transduction of IL-4 and IL-13 and on some genetic studies, IL-4Ralpha was assumed to be one gene giving rise to atopy. One polymorphism existing in the IL-4Ralpha gene, Ile50Val, is verified to correlate with atopy by both genetic and functional aspects. On the contrary, the correlation between another polymorphism on the IL-4Ralpha gene, Arg551Gln, and atopy is still controversial. The strategy used in these studies should lead to identification of other genes involved in atopy.

Humans↗
PubMed2005

The inverse association between the presence of antibody to hepatitis B surface antigen and atopy in young adults.

BACKGROUND: Some bacterial and viral infections may reduce the risk of atopy, and this is based on the concept of their ability to divert the immune system towards the Th1 responses. Most of the hepatitis B virus (HBV) infections occur in the developing countries and this is where atopic disorders are least prevalent. Th1 responses are important for the viral clearance of HBV and also for antibody production. The aim of the study is to investigate whether the presence of antibodies to the hepatitis B surface antigen (anti-HBs) is inversely associated with atopy in adults. METHODS: A random sample of 358 subjects, who were without hepatitis B surface antigen, was recruited; they were aged from 18 to 79 years (105 young adults aged <40 years and 253 older adults aged > 40 years). Determinations of the anti-HBs and skin prick tests using aeroallergens were performed. Those subjects with one or more positive skin reactions (a mean wheal diameter 23 mm) were considered atopic. RESULTS: The prevalence rate of atopy (p=0.035) or the sensitization to Dermatophagoides farinae (p=0.01) was significantly lower in the subjects with anti-HBs than in those subjects without anti-HBs for the young adults, but not for the older adults. The logistic regression analysis that was done on the young adults showed that the presence of anti-HBs was associated with a significantly lower risk of atopy (the odds ratio adjusted for confounding variables = 0.40 [95% CI 0.16-0.981, p=0.046) or with the sensitization to D. farinae (0.20 [0.06-0.65], p = 0.008). CONCLUSION: The presence of anti-HBs produced by a natural HBV infection or vaccination might be inversely associated with atopy in young adults.

Adolescent↗
PubMed2001

Gestational age and occurrence of atopy at age 31--a prospective birth cohort study in Finland.

BACKGROUND: It has been suggested that main risk factors for development of allergic diseases operate already during pregnancy and in early childhood. OBJECTIVE: To study the association between gestational age, birth weight, parity and parental farming with the risk of atopy and asthma in young adults. METHODS: In a prospective birth cohort study, 5192 subjects born in Northern Finland in 1966 were followed up at the age of 31. Skin prick tests were done to three of the most common allergens in Finland and to house dust mite. Data on doctor-diagnosed asthma was obtained from questionnaires. Perinatal data had already been collected during pregnancy. RESULTS: The risk of atopy increased linearly with increasing length of pregnancy among babies born in the 35th weak of gestation or later. Gestational age equal to, or over 40 weeks compared with less than 36 weeks was associated with an increased risk of atopy (multivariate odds ratio 1.65, 95% CI 1.16, 2.34). The association was stronger among farmers' children (P for interaction 0.01). High parity and being a farmer's child (multivariate odds ratio 0.50, 95% CI 0.42-0.60) was associated with decreased risk of atopy. In contrast, no associations were observed for doctor-diagnosed asthma. CONCLUSIONS: The results underline the importance of pregnancy and very early childhood in the development of atopy, and suggest that timing of the environmental exposure is of importance for the immune system. No association was observed for asthma, which may be due to the multifactorial origins of asthma.

Adult↗
PubMed2001

[Atopy among children and adolescents in Copenhagen].

INTRODUCTION: Atopy is related to the presence of rhinitis and asthma, but our knowledge about its longitudinal predictors is limited. METHODS: Data from a 6-yr follow-up study of a population sample of children and adolescents (n = 408), aged 7 to 17 yr. at enrollment, were analysed to investigate the prevalence and predictors of atopy. Case history, including allergic diseases and smoking habits, was elicited by interview and questionnaire. Skin prick test reactivity to common allergens, total serum IgE, airway responsiveness, and pulmonary function were measured. RESULTS: The point prevalence of atopy increased from the first to the second survey, 26% and 44%, respectively; 23% of the participants were atopic only at the second survey. Sensitisation to house dust mites (HDM), grass, dogs, cats, and birch pollen increased significantly in both the males and the females. However, no gender differences in the prevalence of positive reactions were found at the first survey, whereas atopy to grass and HDM was significantly more prevalent in males than in females at the second survey. Analysis of the data solely on participants who were non-atopic at the first survey showed that exposure to maternal smoking (OR 2.0, CI 1.3-3.1; p = 0.002), increased serum IgE (OR 1.7, CI 1.2-2.3; p = 0.001), new asthma (OR 1.6, CI 1.2-2.7; p = 0.03), and new rhinitis (OR 2.1, CI 1.2-3.6; p = 0.01) were associated with an increased risk of a positive skin prick test at the second survey. CONCLUSION: This longitudinal population study showed an increase in the point prevalence of atopy in Danish children and adolescents; and, furthermore, that exposure to maternal smoking during childhood, increased serum IgE, and new symptoms of asthma or rhinitis were associated with an increased risk of developing sensitisation to common aeroallergens in late adolescence.

Adolescent↗
PubMed2002

[Relationships between atopy and bronchial hyper-reactivity in Polish school age children].

OBJECTIVE: To determine the prevalence of atopy and bronchial hyper-reactivity (BHR) and their relationship with wheezing and diagnosed asthma reported in schoolchildren. MATERIAL AND METHODS: In Cracow, 1347 schoolchildren (9.7 +/- 0.7 yrs of age) were surveyed with ISAAC questionnaire. Skin prick tests with 7 aeroallergens and the exercise challenge test for BHR evaluation were carried out. Atopy was established when a positive skin reaction with at least one allergen occurred. The BHR was confirmed in presence of at least 15% decrease of the relative post-exercise peak expiratory flow (D% PEF) or wheezing during or immediately after exercise. RESULTS: Atopy was found in 26.2% of schoolchildren, with a two-fold higher risk in boys/odds ratio (OR) = 2.14; 95% confidence interval (CI) (1.59-2.86)/. In the group of atopic children, wheeze in the last year and diagnosis of asthma occurred significantly more often. The risk of wheeze in last year related to the type of sensitizing allergen and was highest for Der. f./OR = 6.1; 95% CI (3.78-10.16)/, medium for allergens of trees, dog's fur, Der. p., cat's fur and grasses/OR = 5.17; 95% CI (2.27-11.76), OR = 4.36; 95% CI (2.35-8.13), OR = 4.00; 95% CI (3.12-8.01), OR = 3.86; 95% CI (2.18-6.82), OR = 2.58; 95% CI (1.50-4.45), respectively/. In case of Alternaria allergens no correlation with wheeze was observed/OR = 2.71; 95% CI (0.88-8.31)/. BHR was identified in 12.4% of schoolchildren and demonstrated a significant correlation with that reported in the questionnaire: wheeze in the last year/OR = 2.28; 95% CI (1.25-4.14)/, diagnosis of asthma/OR = 2.96; 95% CI (1.38-6.34)/and post-exercise wheeze/OR = 3.17; 95% CI (1.60-6.27)/. Moreover, a significant correlation was demonstrated between atopy and BHR/OR = 1.85; 95% CI (1.22-2.79)/. In the group of children without wheeze in the past and without diagnosis of asthma, BHR was significantly higher in atopic children (positive skin test to in-door allergens) comparing to non-atopic ones, mean D% PEF values were 3.95%, -0.39%, respectively (p. = 0.0014). CONCLUSIONS: In children, there is a significant correlation between atopy and BHR, modified by individual history of wheeze or asthma, sex and allergen type.

Allergens↗
PubMedDate not supplied

The prevalence of atopy in children with antibodies against hepatitis A virus and hepatitis B virus.

To investigate the relationship between atopy and hepatitis A virus (HAV) and hepatitis B virus (HBV) infections, we studied 42 children who had had HAV infection (Group I), 28 children who had had HBV infection (Group II), and 31 children who were seronegative for both HAV and HBV infection (Control group). Serological tests for HAV and HBV infections (anti-HAV IgG, HBsAg, anti-HBc IgG) and allergic skin tests and specific IgE investigations for the detection of atopy were carried out. In this study, there was no significant divergence in the socio-demographic characteristics among the three groups. The rates of specific IgE positivity in children in the HAV seropositive group (11.9%) and in children in the HBV seropositive group (17.8%) were lower than in the control group (35.4%) (p = 0.03 and p = 0.22, respectively). Also, the number of children with respiratory allergic diseases (allergic rhinitis and/or asthma) both in the HAV seropositive group and in the HBV seropositive group were significantly lower than in the control group (p < 0.05). When atopy in all of the groups was evaluated, the prevalence of atopy was found to be more widespread in HAV seronegative children (Adjusted OR, 9.2; 95% CI, 1.7-48.2) and HBV seronegative children (Adjusted OR, 5.9; 95% CI, 1.1-31.8) than in HAV and HBV seropositive children, after adjustment for age, number of older siblings and education of the father. In conclusion, in this study, the prevalence of atopy in children who had had HAV or HBV infection was found to be low, and this situation was considered to be related to the relationship of HAV and HBV infections to poor hygiene and to the fact that these infections occur at early ages in Turkey.

Allergens↗
PubMed1984

Relationship between atopy and bronchial responsiveness to histamine in a random population.

Although there are theoretical reasons to suggest that atopy might predispose to non-allergic bronchial hyperresponsiveness, previous studies have yielded conflicting results. We assessed this by determining the atopic status and bronchial responsiveness to inhaled histamine in 400 randomly selected college students. An atopy score was determined as the number of "+"s from a standard battery of seven allergy prick skin tests each graded from + to +, and the atopic status was graded as non-atopic (no +'s) mildly atopic (1 to 4 +'s), moderately atopic (5 to 8 +'s), or markedly atopic (greater than 8 +'s). Non-allergic bronchial responsiveness to inhaled histamine was measured with a standardized histamine inhalation test from which the histamine provocation concentration producing a 20% FEV1 fall (PC20) was calculated. The prevalence of bronchial hyperresponsiveness to histamine (PC20 less than or equal to 8 mg/ml) was 10.3% in the entire population. There was a progressive increase from 6.1% in the non-atopic group to 33% in the markedly atopic group (p less than 0.001). In 43 subjects with both measurable atopy score (greater than or equal to 1) and PC20 (less than or equal to 16 mg/ml), a regression of atopy score vs. log PC20 produced a small (r = -0.36) but significant (p less than 0.02) correlation. These data indicate a significant relationship exists between atopic status and increased non-allergic bronchial responsiveness to histamine. Although cause and effect cannot be inferred from this study, it is hypothesized that atopy is one factor, among others, which predisposes to non-allergic bronchial hyperresponsiveness.

Adult↗
PubMed1995

[Is atopy a risk factor of occupational asthma?].

General reviews about occupational asthma divide the susceptible allergens capable of initiating asthma into two distinct groups: those of high and of low molecular weight. Atopy would be a risk factor for developing occupational asthma to high molecular weight allergens but not to those of low molecular weight. In this work we have examined several studies and have analysed in a critical manner the relationship which exists between atopy and occupational asthma. The high molecular weight allergens studied were: snow crabs, laboratory animals, flour, proteolytic enzymes and psyllium. Those of low molecular weight were: red cedar, isocyanates, phthalic anhydride. Amongst allergens of high molecular weight there is a undeniable relationship between atopy and sensitisation to the allergen incriminated. However, the relation between atopy and asthma is more debatable except for baker's asthma. For more allergens of low molecular weight, atopy does not seem to favour the appearance of asthma, however, it may play a role in the occurrence of asthma to red cedar. The difference between the two groups of allergens is not as clear-cut as in the work that has appeared up until now and the exclusion of atopics from being hired would appear excessive.

Allergens↗
PubMed1996

Lack of evidence of a significant association between HLA-DR, DQ and DP genotypes and atopy in families with HDM allergy.

BACKGROUND: HLA class II genetic polymorphism has been variably implicated in susceptibility to specific immune responsiveness to house dust mite (HDM) allergens, and may also influence the development of atopy. OBJECTIVE: In order to assess accurately the influence of HLA alleles in the atopic immune response, we typed 22 families selected from 131 previously obtained randomly selected families (i.e. without regard to atopy or asthma), chosen on the basis of two or more members having skin prick reactivity to HDM. METHODS: Each individual was fully typed for HLA-DRB1, DQA1, DQB1 and DPB1 class II alleles using a combination of sequence-specific oligonucleotide probes (SSOP) and sequence-specific primer (SSP) polymerase chain reaction (PCR) typing and direct sequencing. RESULTS: Using appropriate statistical tests, no significant allelic associations were found between any DRB1, DQB1 or DPB1 alleles and atopy or skin prick reactivity to Dermataphagoides pteronyssinus (Der p) or D. farinae (Der f). However, positive associations were found between DQA1*0301 and skin prick reactivity to Der f (P = 0.009) and atopy (P = 0.027). Sib-pair analysis revealed no significant sharing of alleles between affected sib pairs for any of the phenotypes studied. CONCLUSION: These results fail to confirm a previously reported association between the DRB1*04 and 07 haplotypes and atopy, and suggest that HLA class II restriction does not play a major role in the development of the IgE response to domestic house dust mite allergens in the British population.

Allergens↗