Influence of Farm Environment on Asthma during the Life Course: A Population-Based Birth Cohort Study in Northern Finland

We investigated the influence of a farming environment on asthma at three time points from birth to 46 years using the Northern Finland Birth Cohort 1966 (n = 10,926). The prevalence of asthma was investigated by postal questionnaires at 14, 31 and 46 years of age. Exposure to a farming environment was assessed by a postal questionnaire at birth and at 31 and 46 years of age. Odds ratios (ORs) and their 95% confidence intervals (95% CIs) for the prevalence of asthma were obtained from multinomial logistic regression, stratified by sex. Being born in a farmer family was potentially causally associated with lower risk of asthma in males at 31 years of age (OR 0.56, 95% CI 0.37, 0.85) and in females at 46 years of age (OR 0.64, 95% CI 0.44, 0.95). Working as a farmer was not associated with asthma. Exposure to a farming environment in childhood may have a lifelong impact on developing asthma from birth through young adulthood and until middle age, indicating that 'immune deviation' may persist throughout life.

LongITools: Dynamic longitudinal exposome trajectories in cardiovascular and metabolic noncommunicable diseases

The current epidemics of cardiovascular and metabolic noncommunicable diseases have emerged alongside dramatic modifications in lifestyle and living environments. These correspond to changes in our "modern" postwar societies globally characterized by rural-to-urban migration, modernization of agricultural practices, and transportation, climate change, and aging. Evidence suggests that these changes are related to each other, although the social and biological mechanisms as well as their interactions have yet to be uncovered. LongITools, as one of the 9 projects included in the European Human Exposome Network, will tackle this environmental health equation linking multidimensional environmental exposures to the occurrence of cardiovascular and metabolic noncommunicable diseases.

Cough during infancy and subsequent childhood asthma

OBJECTIVES

Wheezing in infancy has been associated with subsequent asthma, but whether cough similarly influences asthma risk has been little studied. We sought to determine whether prolonged cough and cough without cold in the first year of life are associated with childhood asthma.

METHODS

Participants in the Infant Immune Study, a non-selected birth cohort, were surveyed 7 times in the first 9 months of life regarding the presence of wheeze and cough. Cough for more than 28 days was defined as prolonged. Parents were asked at 1 year if the child ever coughed without a cold. Asthma was defined as parental report of physician diagnosis of asthma, with symptoms or medication use between 2 and 9 years. Logistic regression was used to assess adjusted odds for asthma associated with cough characteristics.

RESULTS

A total of 24% (97) of children experienced prolonged cough and 23% (95) cough without cold in the first 9 months, respectively. Prolonged cough was associated with increased risk of asthma relative to brief cough (OR 3.57, CI: 1.88, 6.76), with the risk being particularly high among children of asthmatic mothers. Cough without cold (OR 3.13, 95% CI: 1.76, 5.57) was also independently associated with risk of childhood asthma. Both relations persisted after adjustment for wheeze and total IgE at age 1.

CONCLUSIONS AND CLINICAL RELEVANCE

Prolonged cough in infancy and cough without cold are associated with childhood asthma, independent of infant wheeze. These findings suggest that characteristics of cough in infancy are early markers of asthma susceptibility, particularly among children with maternal asthma.

Relation of early antibiotic use to childhood asthma: confounding by indication?

BACKGROUND

Findings from studies of the relation between early antibiotic use and subsequent asthma have been inconsistent, which may be attributable to methodologic issues.

OBJECTIVE

Our objective was to assess the impact of confounding by indication on the relation of early antibiotic use to childhood asthma through age 5 in a non-selected birth cohort (n=424).

METHODS

Oral antibiotic use was assessed by frequent nurse interviews in the first 9 months of life. Physician-diagnosed active asthma and eczema were assessed by questionnaire at 1, 2, 3, and 5 years, and were considered as ever asthma or ever eczema if positive at any age. Allergen-specific IgE was assessed in plasma at 1, 2, 3, and 5 years. Confounding by indication was investigated by considering the relation of asthma to antibiotic use while controlling for the number of illness visits to a physician in early life.

RESULTS

There was no statistically significant relation of early antibiotic use with physician-diagnosed eczema or allergen-specific IgE. A dose-response relation was evident for antibiotic use with ever asthma (odds ratio [OR]=1.5, P=0.047). Ever asthma also increased significantly with the number of illness visits to a physician (P<0.001). After adjustment for number of illness visits, antibiotic use showed no relation with asthma.

CONCLUSIONS

The relation of asthma to antibiotics in this cohort appears to be an artefact of the strong relation of number of physician visits for illness with both antibiotic use and risk for asthma.

Chronic bronchitis before age 50 years predicts incident airflow limitation and mortality risk

BACKGROUND

Previous studies on the relationship of chronic bronchitis to incident airflow limitation and all-cause mortality have provided conflicting results, with positive findings reported mainly by studies that included populations of young adults. This study sought to determine whether having chronic cough and sputum production in the absence of airflow limitation is associated with onset of airflow limitation, all-cause mortality and serum levels of C-reactive protein (CRP) and interleukin-8 (IL-8), and whether subjects' age influences these relationships.

METHODS

1412 participants in the long-term Tucson Epidemiological Study of Airway Obstructive Disease who at enrolment (1972-1973) were 21-80 years old and had FEV(1)/FVC (forced expiratory volume in 1 s/forced vital capacity) > or = 70% and no asthma were identified. Chronic bronchitis was defined as cough and phlegm production on most days for > or = 3 months in two or more consecutive years. Incidence of airflow limitation was defined as the first follow-up survey with FEV(1)/FVC <70%. Serum IL-8 and CRP levels were measured in cryopreserved samples from the enrolment survey.

RESULTS

After adjusting for covariates, chronic bronchitis at enrolment significantly increased the risk for incident airflow limitation and all-cause mortality among subjects <50 years old (HR 2.2, 95% CI 1.3 to 3.8; and HR 2.2, 95% CI 1.3 to 3.8; respectively), but not among subjects > or = 50 years old (HR 0.9, 95% CI 0.6 to 1.4; and HR 1.0, 95% CI 0.7 to 1.3). Chronic bronchitis was associated with increased IL-8 and CRP serum levels only among subjects <50 years old.

CONCLUSIONS

Among adults <50 years old, chronic bronchitis unaccompanied by airflow limitation may represent an early marker of susceptibility to the effects of cigarette smoking on systemic inflammation and long-term risk for chronic obstructive pulmonary disease and all-cause mortality.

The impact of CD14 polymorphisms on the development of soluble CD14 levels during infancy

CD14 is a receptor involved in the recognition of lipopolysaccharide and other bacterial wall components that may be involved in the balance between infectious and allergic disease and the early polarization towards TH1. Our group has shown an association between polymorphisms in the 5' flanking region of the CD14 gene and plasma soluble CD14 (sCD14) levels at 11 years of age. However, whether this association is present at birth and in infancy remains to be determined. In this study, we measured sCD14 levels in plasma from the umbilical cord (n = 387) and at 3 months (n = 357) and 1 year (n = 312) of age in non-selected healthy infants to assess their relationship with CD14 genotypes at -4190, -2838, -1720 and -260 (relative to translation start site). There was no relation of CD14 genotypes with sCD14 at birth. However, there was a significant association between CD14 genotypes and sCD14 as early as 3 months. Longitudinal analysis suggests that CD14 polymorphisms modulate sCD14 levels up to 1 year of age. This association early in life may have an impact on TH1 polarization and subsequent protection against allergic disease.

Femtosecond absorption dynamics in glass-metal nanocomposites

We report strong optical nonlinearity of glasses embedded with copper and silver nanoparticles. In pump-probe experiments with copper-doped glasses, the observed absorption bleaching with picosecond relaxation time is as high as 22%. Transmission femtosecond measurementsreveal the reverse saturable absorption with nonlinear absorption coefficient of 10(-10)cm/W in both copper- and silver-doped nanocomposites.

Differential control of eosinophil survival by glucocorticoids

Glucocorticoids are effective drugs for eosinophil-related disorders, such as asthma and allergy. Previous studies have demonstrated that glucocorticoids increase eosinophil apoptosis and block the survival effect of submaximal concentrations of interleukin-5 (IL-5). We investigated the effect of glucocorticoids on eosinophil survival in the presence of a higher concentration of IL-5 (1 ng/ml), comparable to IL-5 levels in bronchoalveolar lavage and sputum specimens from patients with asthma. In contrast to incubation in the presence of submaximal concentrations of IL-5, the addition of dexamethasone (DEX) to media containing 1 ng/ml IL-5 led to a significant increase in eosinophil cell viability from 58 +/- 6.9% to 87 +/- 2.4% ( p < 0.005) after 72 hours in culture. We found that RU486 blocked the DEX effect on cell viability confirming that glucocorticoid receptor functions are required. We investigated the possibility that the glucocorticoid enhancement of eosinophil survival may be due to an effect on IL-5 receptor expression. Our results show that the IL-5 associated decrease in IL-5 receptor alpha-subunit expression was blocked significantly after 24 hrs in culture with media containing IL-5 plus DEX compared to IL-5 alone. It is tempting to speculate that the observed glucocorticoid enhancement of eosinophil survival in the presence of elevated concentrations of IL-5 could be a mechanism that contributes to glucocorticoid resistance in asthma.

Dynamic changes in sensitization to specific aeroallergens in children raised in a desert environment

BACKGROUND

Allergen skin test reactivity and total serum IgE are objective measures used to characterize and help diagnose allergic diseases. Cross-sectional studies have shown that overall aeroallergen skin test reactivity increases throughout childhood. However, little attention has been paid to whether individual aeroallergen remittance occurs, which could distort or mask relationships to disease.

OBJECTIVE

To access the incidence and remittance of skin test reactions to individual allergens in children aged 6-11 years.

METHODS

Longitudinal sensitization to six aeroallergens and total IgE were assessed in 828 children raised in the semi-arid US southwest at ages 6 and 11 years.

RESULTS

New sensitization (to any allergen) between 6 and 11 years occurred in 30.2% of children compared with 39.7% before age 6 years. The rate of complete remittance from positive to negative between ages 6 and 11 years was 8.2%, and total IgE at age 6 years was not predictive. Remittance rates for individual allergens were high and variable (19-49%). The perennial allergens Bermuda and Alternaria were early sensitizers and had low remittance rates. Early sensitization to the four seasonal allergens was less common and more subject to remittance with the bulk of sensitization occurring between 6 and 11 years.

CONCLUSION

This study shows that sensitization to individual aeroallergens in childhood is dynamic and indicates the limitation of single point assessment of skin test reactivity.

The association of allergic sensitization in mother and child in breast-fed and formula-fed infants

Human milk contains immunologically active substances potentially capable of altering infant immune response. As part of the prospective Children's Respiratory Study, we assessed whether the association between maternal allergic status and allergic status of the child was altered by breast-feeding. Skin-prick tests for 7 common allergens were administered to 702 6-year-old children and their mothers. The percentage of children sensitized to specific allergens, maternal skin test response to that allergen, and whether or not the child was ever breast-fed was determined. Findings indicated that specific sensitization in the mother was associated with specific sensitization in the child only if the child was breast-fed. This indirectly supports the hypothesis that contents of milk differ with maternal allergic status, and appear to affect allergic status in the child. These results suggest that milk from allergic mothers either promotes a Th2 type immune response or suppresses Th1 immune response in the child.

The autoimmune regulator: a key toward understanding the molecular pathogenesis of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autoimmune disease with autosomal recessive inheritance. APECED is characterized by the breakdown of tolerance to several organ-specific selfantigens. The symptoms of APECED fall into three main categories: autoimmune polyendocrinopathies, chronic mucocutaneous candidiasis, and ectodermal dystrophies. The gene defective in APECED, AIRE, has been cloned and numerous mutations in this gene have been found in patients with APECED. AIRE is predicted to encode a 545-amino-acid protein containing structural domains characteristic for transcription regulators. The protein has been shown to act as a transcriptional activator in vitro. The AIRE protein is mainly localized to the nucleus, where it can be detected as speckles resembling nuclear bodies. In humans, the expression of AIRE has been observed predominantly in immunologically relevant tissues, especially the thymus. Recently, we have shown in the mouse that Aire is also expressed in various tissues and cell types outside the immune system.

A common single nucleotide polymorphism in the CD14 promoter decreases the affinity of Sp protein binding and enhances transcriptional activity

CD14 is a pattern recognition receptor that plays a central role in innate immunity through recognition of bacterial lipoglycans, primarily LPS. Recently, our group has identified a common single nucleotide polymorphism, -159C-->T, in the CD14 proximal promoter. Homozygous carriers of the T allele have a significant increase in soluble CD14, but a decreased total serum IgE. This epidemiologic evidence led us to investigate the molecular basis for the effects of CD14/-159C-->T on CD14 regulation in monocytes and hepatocytes, the two major cell types known to express this gene in vivo. EMSA analysis showed that the T allele results in decreased affinity of DNA/protein interactions at a GC box that contains a binding site for Sp1, Sp2, and Sp3 transcription factors. In reporter assays, the transcriptional activity of the T allele was increased in monocytic Mono Mac 6 cells, which express low levels of Sp3, a member of the Sp family with inhibitory potential relative to activating Sp1 and Sp2. By contrast, both alleles were transcribed equivalently in Sp3-rich hepatocytic HepG2 cells. Our data indicate that the interplay between CD14 promoter affinity and the [Sp3]:[Sp1 + Sp2] ratio plays a critical mechanistic role in regulating transcription of the two CD14 alleles. Variation in a key gene of innate immunity may be important for the pathogenesis of allergy and inflammatory disease through gene-by-gene and/or gene-by-environment interactions.

Factor analysis of asthma and atopy traits shows 2 major components, one of which is linked to markers on chromosome 5q

BACKGROUND

A variety of definitions of asthma and atopy traits have been used in genetic studies. The variables used may be correlated, increasing the likelihood of type I error.

OBJECTIVE

We sought to clarify and quantify phenotypes that may be characterized by related traits. Principal components and factor analysis were applied to the correlation matrix of asthma and atopy traits before linkage analysis.

METHODS

Factor analysis was performed on 468 Hispanic and non-Hispanic white children enrolled in the Tucson Children's Respiratory Study, with complete information on 24 items, including skin test response to 7 allergens, total serum IgE levels, presence or absence of asthma attacks, wheezing episodes, hay fever, and cough. Factor score coefficients were then applied to all siblings (n = 877), and quantitative factor scores were derived. Single-point and multipoint nonparametric sib-pair analyses were performed to assess linkage to markers on chromosome 5q31-33. Analyses were also performed for individual items.

RESULTS

Two main factors were identified: Factor I had high loadings on atopic items, including skin test responses, IgE, and hay fever, and Factor II had high loadings that included asthma diagnosis, wheezing, cough, and Alternaria species skin test response. Factors I and II were correlated at an r value of 0.19. For the quantitative factor scores, significant single-point linkage (P < .0001) was demonstrated only for atopic Factor I, and a peak multipoint LOD score of 2.7 was seen for marker D5S479. Multipoint LOD scores for individual items were 1.1 or less.

CONCLUSION

These analyses suggest evidence for a locus or loci mapping to chromosome 5q31-33 associated with this composite atopic phenotype.

CD14: a bridge between innate immunity and adaptive IgE responses

Total IgE levels are known to be under genetic control. Linkage studies have indicated that one or more loci on chromosome 5q may control total IgE, as well as asthma and bronchial hyperresponsiveness to non-specific stimuli. Our group has undertaken a systematic analysis of chromosome 5q, and has recently characterized five single nucleotide polymorphisms at position -1619, -1359, -1145, -809, and -159 in the promoter of the gene encoding CD14, the myeloid pattern recognition receptor that is critical for efficient innate immune responses to lipopolysaccharide and bacterial ligands. Individuals homozygous for the three major CD14 haplotypes found in the Children Respiratory Study population (n = 390) were analyzed for serum levels of total IgE and soluble CD14. A strong inverse correlation was found between these two parameters, i.e. carriers of the -1359T/-1145A/-159C haplotype had the highest levels of IgE, and the lowest levels of sCD14. Conversely, carriers of the -1359G/-1145G/-159T haplotype had the highest levels of sCD14 and the lowest IgE values. Our results suggest that genetic variation in CD14, a key gene of innate immunity, may modulate the effects that exposure to bacterial ligands has on the development of Th2 responses.

Isolation of high quality RNA from bilberry (Vaccinium myrtillus L.) fruit

A simple and efficient method is described for isolating high quality RNA from bilberry fruit. The procedure is based on the use of hexadecyltrimethyl ammonium bromide (CTAB), polyvinylpyrrolidone (PVP), and beta-mercaptoethanol in an extraction buffer in order to eliminate the polysaccharides and prevent the oxidation of phenolic compounds. This method is a modification of the one described for pine trees, and yields high-quality RNA suitable for cDNA based methodologies. This method is applicable for a variety of plant tissues.

Relation between infantile colic and asthma/atopy: a prospective study in an unselected population

OBJECTIVE

To assess whether children with history of infantile colic may be at increased risk of subsequently developing asthma and/or atopy.

METHODS

We used data collected in a large, prospective study from an unselected population. Infantile colic and concurrent feeding method were determined from the 2-month well-infant visit form completed by the physician for 983 children who were enrolled at birth. Markers of atopy (total serum immunoglobulin E and allergy skin prick test), allergic rhinitis, asthma, wheezing, and peak flow variability were the main outcome measures studied at different ages between infancy and 11 years.

RESULTS

Ninety (9.2%) children had infantile colic. Prevalence of colic was similar among children fed either breast milk or formula. There was no association between infantile colic and markers of atopy, asthma, allergic rhinitis, wheezing, or peak flow variability at any age.

CONCLUSION

Our data cannot support the hypothesis that infantile colic provides increased risk for subsequent allergic disease or atopy.

Differences in proliferation of the hematopoietic cell line TF-1 and cytokine production by peripheral blood leukocytes induced by 2 naturally occurring forms of human IL-3

BACKGROUND

A naturally occurring polymorphism in the coding region of the human IL3 gene leads to a change in amino acid residue 8 from proline to serine.

OBJECTIVE

We sought to determine whether the 2 different forms of IL-3 varied in function. These different forms are available as recombinant proteins (recombinant human IL-3/proline 8 [rhIL-3/P8] and recombinant human IL-3/serine 8 [rhIL-3/S8]).

METHODS

The erythroleukemic cell line TF-1 was incubated with varying concentrations of rhIL-3/P8 or rhIL-3/S8 to determine the capacity of each type of IL-3 to induce proliferation. Human leukocytes were primed with rhIL-3/P8 or rhIL-3/S8 for up to 24 hours and then stimulated with anti-IgE and assessed for leukotrienes (LTs), IL-4, and TNF-alpha.

RESULTS

Proliferation of TF-1 cells was induced by both forms of IL-3 at 48 and 72 hours but to a greater degree by rhIL-3/P8. In contrast, the mean fold increase over control values of LT and IL-4 production was higher after priming the cells with rhIL-3/S8 versus rhIL-3/P8. Additionally, TNF-alpha production was greater (and reached significance only) for rhIL-3/S8. This activity was independent of IgE and thus directly stimulated by IL-3. Studies with basophil-enriched and basophil-depleted cell preparations revealed that LT production was evident only from the former and TNF-alpha only from the latter.

CONCLUSION

We conclude that the 2 naturally occurring forms of human IL-3 have similar spectra of activities on cells with IL-3 receptors, but the 2 forms have reversed relative efficacies for promoting proliferation (rhIL-3/P8 > rhIL-3/S8) compared with priming or inducing mediator secretion (rhIL-3/S8 > rhIL-3/P8).

Relation of two different subtypes of croup before age three to wheezing, atopy, and pulmonary function during childhood: a prospective study

OBJECTIVE

Some retrospective evidence suggests that children with a history of croup may be at increased risk of subsequently developing asthma, atopy, and diminished pulmonary function. The objective of this study was to determine the long-term outcome of croup (as diagnosed by a physician) in early life.

METHODS

Lower respiratory illnesses (LRIs) in the first 3 years of life were assessed in 884 children who were enrolled in a large longitudinal study of airway diseases at birth. Pulmonary function tests, markers of atopy, and wheezing episodes were studied at different ages between birth and 13 years.

RESULTS

Ten percent of children had croup with wheeze (Croup/Wheeze), 5% had croup without wheeze (Croup/No Wheeze), 36% had another LRI (Other LRI), and 48% had no LRI. Respiratory syncytial virus was more frequently isolated in children with Croup/Wheeze and Other LRI than in those with Croup/No Wheeze. There was no association between croup in early life and markers of atopy measured during the school years. Only children with Croup/Wheeze and with Other LRI had a significant risk of subsequent persistent wheeze later in life. Significantly lower levels of indices of intrapulmonary airway function were observed at ages <1 (before any LRI), 6, and 11 years in children with Croup/Wheeze and Other LRI compared with children with No LRI. Conversely, inspiratory resistance before any LRI episode was significantly higher in infants who later developed Croup/No Wheeze than in the other 3 groups.

CONCLUSIONS

We distinguish 2 manifestations of croup with and without wheezing. Children who present with croup may or may not be at increased risk of subsequent recurrent lower airway obstruction, depending on the initial lower airway involvement, and preillness and postillness abnormalities in lung function associated with this condition.

Subcellular location and expression pattern of autoimmune regulator (Aire), the mouse orthologue for human gene defective in autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED)

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), also known as autoimmune polyglandular syndrome Type I (APS1), is an autosomal recessive autoimmune disease caused by mutations in a gene designated as AIRE (autoimmune regulator). Here we have studied the expression of Aire in transfected cell lines and in adult mouse tissues. Our results show that Aire has a dual subcellular location and that it is expressed in multiple immunologically relevant tissues such as the thymus, spleen, lymph nodes, and bone marrow. In addition, Aire expression was detected in various other tissues such as kidney, testis, adrenal glands, liver, and ovary. These findings suggest that APECED protein might also have a function(s) outside the immune system.(J Histochem Cytochem 49:197-208, 2001)

Autoimmune polyendocrine syndrome type 1 (APS I) in Norway

OBJECTIVE

The aim of the present study was to investigate Norwegian patients with autoimmune polyendocrine syndrome type I (APS I), with respect to occurrence and clinical presentation, reactivity towards different autoantigenes and mutations in the autoimmune regulator (AIRE) gene.

PATIENTS

Twenty Norwegian patients from 15 families with APS I (11 males, nine females; mean age 26 years, range 4--54) were included by contacting all major hospitals in Norway.

METHODS

Clinical data was collected from both patients and their physicians by the use of questionnaires and patient records. Autoantibodies were analysed using radioimmunoassays based on antigen synthesized by in vitro transcription and translation. AIRE mutations were determined by DNA sequence analysis.

RESULTS

The prevalence of APS I in Norway was estimated to be about 1 : 80,000 individuals. We found about the same distribution of disease characteristics as has been reported in Finnish patients. The diagnosis was delayed in many individuals. In two thirds of the cases, the patients were admitted in Hospital with acute adrenal insufficiency or hypocalcaemic crisis. Forty percent of these patients already had one of the main disease manifestations. Four different mutations in the AIRE gene were found in the Norwegian cohort. A 13-bp deletion in exon 8 (1085--1097(del)) was the most frequent mutation, present in 22/40 (55%) of the alleles. Eighty-five percent of the patients had either autoantibodies against 21 hydroxylase or aromatic L-amino acid decarboxylase. Five of eight women (age > 13 years) had ovarian failure, and all of these had antibodies against side-chain cleavage enzyme (P = 0.0002).

CONCLUSION

Norwegian patients with APS I clinically resemble patients from Finland and other European countries. The diagnosis APS I must be considered in children and adolescents with chronic mucocutaneous candidiasis, autoimmune adrenocortical failure or hypoparathyroidism in order to avoid fatal complications. Analysis of autoantibodies and mutational analysis of the AIRE gene are valuable diagnostic tools, especially in the early stages of the disease.

Workshop to identify critical windows of exposure for children's health: immune and respiratory systems work group summary

Fetuses, infants, and juveniles (preadults) should not be considered simply "small adults" when it comes to toxicological risk. We present specific examples of developmental toxicants that are more toxic to children than to adults, focusing on effects on the immune and respiratory systems. We describe differences in both the pharmacokinetics of the developing immune and respiratory systems as well as changes in target organ sensitivities to toxicants. Differential windows of vulnerability during development are identified in the context of available animal models. We provide specific approaches to directly investigate differential windows of vulnerability. These approaches are based on fundamental developmental biology and the existence of discrete developmental processes within the immune and respiratory systems. The processes are likely to influence differential developmental susceptibility to toxicants, resulting in lifelong toxicological changes. We also provide a template for comparative research. Finally, we discuss the application of these data to risk assessment.

Workshop to identify critical windows of exposure for children's health: immune and respiratory systems work group summary

Fetuses, infants, and juveniles (preadults) should not be considered simply "small adults" when it comes to toxicological risk. We present specific examples of developmental toxicants that are more toxic to children than to adults, focusing on effects on the immune and respiratory systems. We describe differences in both the pharmacokinetics of the developing immune and respiratory systems as well as changes in target organ sensitivities to toxicants. Differential windows of vulnerability during development are identified in the context of available animal models. We provide specific approaches to directly investigate differential windows of vulnerability. These approaches are based on fundamental developmental biology and the existence of discrete developmental processes within the immune and respiratory systems. The processes are likely to influence differential developmental susceptibility to toxicants, resulting in lifelong toxicological changes. We also provide a template for comparative research. Finally, we discuss the application of these data to risk assessment.

A cluster of seven tightly linked polymorphisms in the IL-13 gene is associated with total serum IgE levels in three populations of white children

BACKGROUND

Increased levels of total serum IgE are a strong risk factor for the development of asthma. IgE is also involved in host defenses against parasites and fungi. Linkage of total serum IgE with markers located close to the 3 Mb cluster of cytokine genes in chromosome 5q31 has been reported. IL-4 or IL-13 are regarded as essential for IgE synthesis.

OBJECTIVE

We tested whether polymorphisms in the IL-13 gene might explain the linkage between chromosome 5q31 and total serum IgE levels.

METHODS

We used denaturing HPLC to detect polymorphisms in overlapping PCR fragments of the IL-13 gene including promoter and 3' untranslated regions. After sequencing was performed to identify the locations of the polymorphisms, PCR and primer-induced restriction site assays were used to genotype subjects in 3 unselected populations.

RESULTS

We report here 7 polymorphisms (6 novel) in IL-13. Four of these polymorphisms are tightly linked to a variant in the terminal portion of the coding region of the gene that results in a predicted amino acid change in residue 130 (Arg130Gln). The Gln form is strongly associated (P =.000002) with increased serum IgE levels in 3 different populations comprising a total of 1399 children. Two additional polymorphisms in the promoter region of IL-13 are more loosely linked to Arg130Gln and are also less significantly associated with total serum IgE levels.

CONCLUSION

These data suggest that the Arg130Gln polymorphism in IL-13, or others in close linkage with it, is associated with the development of the elevated serum IgE phenotype.

Autoantibodies against aromatic L-amino acid decarboxylase identifies a subgroup of patients with Addison's disease

Autoantibodies against aromatic L-amino acid decarboxylase (AADC) are present in about 50 percent of sera from patients with autoimmune polyendocrine syndrome type I (APS I) but absent in sera from patients with different organ-specific autoimmune diseases, such as insulin-dependent diabetes mellitus, Hashimoto's thyroiditis, and Graves' disease. AADC is expressed in the pancreatic beta-cells, the liver, and the nervous system; and the presence of AADC antibodies has been shown to correlate to hepatitis and vitiligo in APS I patients. Among 101 investigated patients with autoimmune Addison's disease, 15 had high titers of AADC antibodies. According to the clinical characteristics of these patients, only 3 had APS I. The remaining 12 had either isolated Addison's disease or associated diabetes mellitus, hypothyroidism, vitiligo, alopecia, gonadal failure, and pernicious anemia. Autoantibodies against 21-hydroxylase were present in 9 of 12, whereas autoantibodies against side-chain cleavage enzyme and 17alpha-hydroxylase were present in 3 of 12. Two patients had only autoantibodies against AADC. DNA was available from 3 of these 12 patients. One of the patients, a woman with Addison's disease, autoimmune thyroiditis, and premature menopause was heterozygous for a point mutation (G1021A, Val301Met) in the first plant homeodomain zinc finger domain of the autoimmune regulator (AIRE) gene. The presence of AADC autoantibodies identifies patients with APS I and a subgroup of Addison patients who may have a milder atypical form of APS I or represent a distinct entity. Measurement of autoantibodies against AADC should be included in the evaluation of Addison's disease.

Familial aggregation and segregation analysis of eosinophil levels

The number of circulating eosinophils is associated with the risk of asthma in population samples. Therefore, eosinophil levels may be an intermediate phenotype for asthma amenable to genetic analysis. We examined familial aggregation of the number of eosinophils x 10(6) L(-1) and the percentage of eosinophils based on a 300 count differential in 644 Hispanic and non-Hispanic white families, with 2, 097 subjects, enrolled in the Tucson Children's Respiratory Study. Both measures were adjusted for age, season and year at the time blood was drawn, sex, and ethnicity. Segregation analysis was conducted in the 458 non-Hispanic white families, as there were no significant familial correlations in the Hispanic families, and there was significant heterogeneity by ethnic group. Familial correlations (rho) in the non-Hispanic white families were as follows: mother-father, 0.05; mother-child, 0.18 (p < 0.001); father-child, 0.07; sibling-sibling, 0.31 (p < 0.001). Without covariates analyses indicated a polygenic/multifactorial mode of inheritance. After adjusting for current and past asthma an oligogenic mode of inheritance was suggested, plus additional residual familial components that were mainly maternally mediated. This study supports the notion of multiple, relatively common genes interacting to determine genetic susceptibility to asthma. Holberg CJ, Halonen M, Wright AL, Martinez FD. Familial aggregation and segregation analysis of eosinophil levels.

Breast-feeding, maternal IgE, and total serum IgE in childhood

BACKGROUND

There is controversy regarding the relationship of the effect of breast-feeding on markers of allergy such as total serum IgE in childhood.

OBJECTIVE

This study, using longitudinal data, tested the hypothesis that the relation of breast-feeding to IgE in childhood differs depending on maternal total IgE level.

METHODS

Total serum IgE was assessed with the paper radioimmunosorbent test at 4 ages in nonselected children enrolled at birth into the prospective Tucson Children's Respiratory Study. Children were classified as never breast-fed, breast-fed less than 4 months, or breast-fed 4 months or longer, on the basis of physician report or questionnaires completed by parents by the time the child was 18 months old. A longitudinal random effects model was used to test for group differences and temporal trends in IgE for children classified with reference to maternal IgE (high tertile vs all others) and breast-feeding history. A total of 664 children with 1457 observations were included.

RESULTS

Among children whose mothers were in the 2 lower tertiles of IgE, breast-feeding was associated with lower total serum IgE at age 6 years (24.2 vs 44.3 IU/mL for never breast-fed children; P <.02); similar trends existed at age 11 years. In contrast, for children whose mothers were in the highest tertile of IgE, breast-feeding of 4 months or longer was associated with higher IgE levels in the child compared with those never breast-fed or breast-fed less than 4 months (97.0 vs 38.9 IU/mL; P <. 005). These cross-sectional analyses were confirmed with the longitudinal random effects model, which also showed no effect of confounders. Paternal IgE showed no similar relation with child IgE.

CONCLUSION

Breast-feeding appears to have paradoxic relations with IgE in childhood, depending on maternal IgE level. These findings may help explain the contradictory results found in other investigations of the relation of breast-feeding to allergic symptoms and markers.

Respiratory syncytial virus in early life and risk of wheeze and allergy by age 13 years

BACKGROUND

The relation between lower respiratory tract illnesses in early life caused by the respiratory syncytial virus (RSV) and the subsequent development of wheezing and atopy in childhood is not well understood. We studied this relation in children who had lower respiratory tract illnesses that occurred before 3 years of age.

METHODS

Children were enrolled at birth and cases of lower respiratory tract illness were ascertained by a physician. Viral tests were done for specimens collected at the time of the illness. Children were classified into five groups according to type and cause of lower respiratory tract illness. Children were then followed prospectively up to age 13, and we measured frequency of wheezing, pulmonary function, and atopic status (allergy skin-prick tests, serum IgE concentrations).

FINDINGS

RSV lower respiratory tract illnesses were associated with an increased risk of infrequent wheeze (odds ratio 3.2 [95% CI 2.0-5.0], p < 0.001), and an increased risk of frequent wheeze (4.3 [2.2-8.7], p < or = 0.001) by age 6. Risk decreased markedly with age and was not significant by age 13. There was no association between RSV lower respiratory tract illnesses and subsequent atopic status. RSV lower respiratory tract illnesses were associated with significantly lower measurements of forced expiratory volume (2.11 [2.05-2.15], p < or = 0.001) when compared with those of children with no lower respiratory tract illnesses, but there was no difference in forced expiratory volume after inhalation of salbutamol.

INTERPRETATION

RSV lower respiratory tract illnesses in early childhood are an independent risk factor for the subsequent development of wheezing up to age 11 years but not at age 13. This association is not caused by an increased risk of allergic sensitisation.

Two subphenotypes of childhood asthma that differ in maternal and paternal influences on asthma risk

Asthma is a phenotypically heterogeneous disease. Two subgroups are defined here based initially on skin test reactivity to the allergen Alternaria at age 6 from among a large population of children born and raised in the Southwestern desert environment of Tucson, Arizona. When compared with asthma among Alternaria-positive subjects, asthma among Alternaria-negative subjects was associated with lower levels of total serum IgE, no relation to local aeroallergen skin tests, a younger age at diagnosis, greater remittance by age 11, and more frequent wheezing lower respiratory illnesses (LRIs) in the first year of life. Despite the difference in total serum IgE, however, IgE concentrations were significantly higher in each asthma group compared with its respective control group. Asthma in each parent contributed approximately equivalent risk for Alternaria-positive asthma in the child. However, neither parental skin test sensitization nor total serum IgE levels provided risk for asthma in the child. Inheritance patterns for Alternaria-negative asthma revealed a contribution from maternal but not paternal asthma. Thus, dividing asthma in children at age 6 into Alternaria-positive and Alternaria-negative groups identifies subphenotypes that are further distinguished by differences in phenotypic markers and parental influences.

Total serum IgE and its association with asthma symptoms and allergic sensitization among children

BACKGROUND

Asthma and wheezing during childhood are associated with elevated total serum IgE and with allergic sensitization to local aeroallergens. However, little is known about the longitudinal relationship between total serum IgE and the development of wheezing and allergic sensitization during childhood.

OBJECTIVE

The purpose of our investigation was to determine the relationship between total serum IgE and the development of wheezing and allergic sensitization in childhood.

METHODS

Our study subjects were participants in the Tucson Children's Respiratory Study who underwent an IgE measurement in at least 1 of 3 surveys (at years 1, 6, and 11) and complete allergy skin tests during the latter 2 surveys. The children's phenotypes were categorized on the basis of skin test response (never, early, and late) and wheezing status (never, early, late, and persistent). Repeated-measures analyses were used, allowing subjects to be included who had unequal numbers of IgE observations (a total of 263 boys and 277 girls).

RESULTS

We found that total serum IgE levels track with age: subjects with high serum IgE levels less than 1 year old continued to have high IgE levels at ages 6 and 11 years. Both persistent wheezing and early sensitization were associated with high serum IgE levels at all ages. Boys who had late or persistent wheezing or who were sensitized early or late had high serum IgE levels as early as age 9 months, whereas only girls with persistent wheezing and early sensitization had elevated IgE levels at that age. Children who wheezed only in the first years of life and not after (ie, those with early wheezing) had serum IgE levels that were not different from those of nonwheezing children.

CONCLUSION

On the basis of these findings we conclude that although total serum IgE tracks with age, children who are predisposed to persistent wheezing and early sensitization to local aeroallergens already have high levels of IgE at age 9 months. This suggests that the predisposition to respond to environmental stimuli through high levels of IgE precede early allergic sensitization, indicating that there may be a common defect in the development of the immune system involving IgE production and early allergic sensitization.

Association of radiologically ascertained pneumonia before age 3 yr with asthmalike symptoms and pulmonary function during childhood: a prospective study

Epidemiologic evidence suggests an association between reports of pneumonia in early life and the subsequent development of diminished lung function. However, no studies are available in which the diagnosis of pneumonia was based on radiologic evidence. Lower respiratory illnesses with or without a radiologically confirmed diagnosis of pneumonia were assessed in a study of 888 children enrolled at birth. Pulmonary function tests, markers of atopy, asthma diagnosis, and prevalence of respiratory symptoms were assessed at different ages between birth and 11 yr. Incidence of pneumonia during the first 3 yr of life was 7.4%. Respiratory syncytial virus was the most frequent agent identified both in children with pneumonia and in those with lower respiratory tract illness (LRI) without pneumonia (36.4% versus 35.6%, respectively). Children with a diagnosis of pneumonia were more likely to have physician-diagnosed asthma and current wheezing at ages 6 and 11 yr than were those who had no LRIs. When compared with children without LRIs, those with a diagnosis of pneumonia had lower levels of maximal flows at FRC at mean age of 2 mo (albeit not significantly) and at age 6 yr, and lower levels of FEV1 and FEF25-75 at age 11 yr. These deficits were independent of known confounders, including wheezing at the time of study, and were partly and significantly reversed after administration of a bronchodilator. We conclude that children with radiologically confirmed pneumonia have diminished airway function that is probably present shortly after birth. These deficits are at least in part due to alterations in the regulation of airway muscle tone.

A Polymorphism* in the 5' flanking region of the CD14 gene is associated with circulating soluble CD14 levels and with total serum immunoglobulin E

Total serum immunoglobulin (Ig)E levels are genetically regulated, but the mechanism of inheritance is not well understood. Cytokines produced by T-helper (Th)1 and Th2 lymphocytes control IgE synthesis. Bacterial antigens may favor the development of Th1 cells from naive CD4-positive T cells through a CD14-dependent pathway. CD14 is constitutively expressed on the surface of monocytes and macrophages, and is also present in serum in a soluble form (sCD14). The CD14 gene maps to chromosome 5q31.1, a candidate region for loci regulating total serum IgE. We hypothesized that genetic variants in the CD14 gene could influence Th-cell differentiation and thus total serum IgE. We identified a C-to-T transition at base pair -159 from the major transcription start site (CD14/-159). Among 481 children recruited from a general population sample, frequency of allele C was 51.4%. TT homozygotes had significantly higher sCD14 levels than did carriers of both the CC and CT genotypes (P = 0.01). TT homozygotes also had significantly lower levels of IgE than did carriers of the other two genotypes, but differences were significant only among children who were skin test-positive to local aeroallergens (P = 0.004). There was no association between CD14/-159 and either interleukin (IL)-4 or interferon (IFN)-gamma responses by peripheral blood mononuclear cells. However, IFN-gamma and IL-4 responses were positively and negatively correlated, respectively, with serum sCD14 levels. We conclude that CD14/-159 plays a significant role in regulating serum sCD14 levels and total serum IgE levels.

Perinatal events in the development of asthma

Many potential factors are likely involved in the pathogenesis of asthma. These include prenatal, peripartum, and postnatal influences. Prenatally, genetic endowment, maternal smoking, in utero allergen sensitization, and alterations in maternal immune function, especially at the placental level, may increase the risk for asthma and atopy. In the peripartum period, suspected factors include obstetric practices (eg, the use of prostaglandins, hormones, and other agents) and prematurity. Postnatally passive smoke exposure, neonatal or early childhood infections and breast-feeding are under increasing scrutiny as to their possible role in the development of asthma. Despite the volumes of work already reported, much more is left to be done to sort out the complex interrelationships of these and other as yet unsuspected influences on the development of asthma.

Differential immune responses to acute lower respiratory illness in early life and subsequent development of persistent wheezing and asthma

BACKGROUND

Recent epidemiologic evidence suggests that 2 wheezing syndromes coexist in early life: transient wheezing, limited to early childhood, and persistent wheezing, which starts in early childhood and persists beyond that age.

OBJECTIVE

Whether the nature of the immune response occurring during acute lower respiratory illnesses (LRIs) in infancy differs between these 2 groups of wheezers has yet to be determined.

METHODS

We compared total serum IgE levels and peripheral blood eosinophil counts obtained during the acute phase of the first LRI with those obtained during the convalescent phase or with well-baby samples in persistent (n = 49) and transient early wheezers (n = 88), as well as in children who had only nonwheezing LRIs (n = 43) during the first 3 years of life.

RESULTS

Total serum IgE levels were significantly higher (P =.008) during the acute phase compared with the convalescent phase of the LRI in persistent wheezers, a response not observed in transient early wheezers (P =.7). Peripheral blood eosinophil counts were significantly reduced during the acute phase of the LRI (P =.009) in transient early wheezers, a response not observed among persistent wheezers (P =.7). Acute responses in children who had nonwheezing LRIs only were similar to those seen in transient early wheezers.

CONCLUSION

Alterations in acute immune response to viral infection may be detected at the time of the first wheezing episode in subjects who will go on to have persistent wheezing symptoms.

Antenatal interventions in childhood asthma

The occurrence of asthma in most young children is likely to result from altered or disrupted immune maturation. The persistence of Th2-like lymphocyte responses to common allergens rather than the extinction of immune response (immune tolerance) or the deflection of response to a Th1 pattern (immune deviation) may underlie the development of asthma and the atopic phenotype. It is likely that this failure of normal immune maturation begins early in life, and that both genetic predisposition and environmental factors operating at critical times act jointly to cause it. There is clear evidence that the development of immune response capability begins in utero, and that maternal allergic and other exposures can affect this process before birth. While there is some evidence that the onset of atopy or atopic symptoms can be ameliorated or delayed in early life by reducing maternal prenatal allergen exposure (either food or inhaled allergens), there is currently no convincing evidence that prenatal maternal allergen avoidance will diminish asthma incidence in children. There are similarly no data available to evaluate if dietary antioxidants, postulated but unproven to have a protective role on airway reactivity and asthma incidence and severity in adults, have any protective role in utero. In contrast, maternal smoking during pregnancy has been shown in several studies to be associated with reductions in pulmonary function measures (flows at low lung volumes) in both infants and older children that are consistent with abnormalities seen in asthmatics. This finding, coupled with the clear association of postnatal environmental tobacco smoke exposure with increased wheezing and asthma risk in children, make maternal smoking cessation the prenatal intervention most likely to be effective in reducing asthma risk in children.

Platelet-activating factor induction of activator protein-1 signaling in bronchial epithelial cells

Platelet-activating factor (PAF) has been implicated in the pathogenesis of allergic and inflammatory events in the airway. In the present study, we sought to determine if PAF receptors are present on human bronchial epithelial cells and whether PAF binding to these receptors leads to activation of activator protein-1 (AP-1)-mediated transcription. Radioligand binding studies demonstrated specific binding sites for the PAF antagonist [3H]WEB 2086 (3-[4-(2-chlorophenyl)-9-methyl-6H-thieno[3,2-f]-[1,2,4]triazolo[4,3- a][1,4]diazepine-2-yl]-1-(4-morpholinyl)-1-propanone) on primary bronchial epithelial cells with an equilibrium dissociation constant (Kd) = 9.8 nM and maximal density of binding sites (Bmax) = 42.4 fmol/mg of protein. The expression of PAF receptors in these cells was further confirmed by reverse transcriptase-polymerase chain reaction, which revealed amplification products derived from PAF receptor mRNA corresponding to transcripts 1 and 2. In the bronchial epithelial cell line BEAS-2B transfected with an expression plasmid for the human PAF receptor, PAF stimulation increased AP-1 DNA binding activity as determined by electrophoretic mobility shift assays. The Fos and Jun family proteins were identified as components of the DNA-protein complexes by anti-peptide antibodies in gel supershift assays. Additionally, PAF significantly induced AP-1 mediated transcription which was dependent on the expression of PAF receptors. The PAF antagonist WEB 2086 blocked the PAF effect but not that induced by 12-O-tetradecanoyl phorbol-13-acetate, indicating the specificity of the PAF response. These results indicate that activation of airway epithelial cells through stimulation of PAF receptors includes up-regulation of the nuclear transcription factor AP-1 and AP-1 transcriptional activity.

Evidence for platelet-activating factor receptor subtypes on human polymorphonuclear leukocyte membranes

Platelet-activating factor (PAF) is a potent phospholipid mediator that acts through specific cell surface receptors. The existence of PAF receptor subtypes has been suggested by functional and radioligand binding studies in a variety of cells and tissues. This report addresses this issue more directly and demonstrates differences between specific PAF receptors in human polymorphonuclear leukocytes (PMNs) and COS-7 cells transfected with the cloned human PAF receptor gene. The presence of more than one receptor in human PMNs is supported by three different studies. First, the Kd from the saturation isotherms for the binding of [3H]WEB 2086 on PMNs was 7-fold larger (Kd = 29.2 nM) than the kinetic Kd (4.2 nM). Second, the pseudo-Hill slope determined from the saturation experiments with PMNs was significantly lower than unity (0.69 +/- 0.05 SEM), and the saturation Kd values for transfected COS-7 (Kd = 9.6 nM) and PMN membranes were significantly different. These results contrasted with those for the transfected COS-7 cells, which showed a Kd from the saturation isotherms similar to that of the kinetic Kd (3.2 nM) and a pseudo-Hill slope that was not different from 1.0. Third, when the radiolabeled ligand [3H]WEB 2086 was increased in concentration from 10 to 50 nM in inhibition experiments with the human PMN membranes, the Ki increased, indicative of binding mainly to receptors with lower affinity. These results suggest that PAF receptor subtypes exist in human PMNs based on distinct radioligand binding characteristics from the human cloned PAF receptor.

Alternaria as a major allergen for asthma in children raised in a desert environment

The relationships of asthma and allergic rhinitis with individual immediate skin test responses were examined for preferential associations and for changes with age in children raised in a semiarid environment. Prevalence of physician-diagnosed asthma was 9.8% at age 6 (n = 948) and 15.5% at age 11 (n = 895). Immediate skin test responses to Bermuda grass were the most prevalent among children with allergic rhinitis and control subjects, whereas responses to the mold, Altenaria alternata, were the most prevalent among asthmatics. Skin test responses for crude house dust, Dermatophagoides farinae, and cat had low prevalences in all groups. By logistic regression, Alternaria was the only allergen independently associated with increased risk for asthma at both ages 6 and 11. Allergic rhinitis showed independent association with sensitization to Bermuda grass and mulberry tree pollen at age 11 but did not show an independent relation to any single allergen at age 6. Logistic regression further revealed that persistent asthma (diagnosed before age 6) was independently associated with Alternaria skin tests at both ages 6 and 11, whereas new asthma (diagnosed after age 6) was associated with Alternaria skin tests at age 6 but not at age 11. We conclude that Alternaria is the major allergen associated with the development of asthma in children raised in a semiarid environment and that skin test responses at age 6 are more closely linked to asthma than those at age 11.

Segregation analysis of physician-diagnosed asthma in Hispanic and non-Hispanic white families. A recessive component?

The inheritance of asthma, evident from its high family concordance, is not well understood. To investigate whether asthma may be inherited through a major gene with two alleles, segregation analyses were conducted in 3,369 individuals from 906 nuclear families enrolled, without selection, in a longitudinal study of respiratory health in Tucson, Arizona. Physician-diagnosed asthma and its age of onset were ascertained for each family member when children were at a mean age of 7 yr. Age of asthma diagnosis was allowed for in analyses, and the impact of the covariate total serum IgE level on age of onset was examined. Segregation analyses were conducted with and without residual family effects, with and without the covariate IgE. The hypothesis of a single two-allele locus for asthma was rejected. However, depending on the method of assessment of the residual familial effects, either a polygenic/multifactorial mode of inheritance alone, or an oligogenic model with some evidence of a recessive component present in the population with the high frequency of 0.67, were compatible with the data. Results were unchanged with the addition of the covariate IgE.

Serum levels of the soluble low affinity receptor for IgE and soluble interleukin-2 receptor in childhood, and their relation to age, gender, atopy and allergic disease

Identifying immune factors associated with the development of atopy can enhance our understanding of the in vivo mechanisms involved and may have utility in paradigms designed to prevent disease. Two candidates suggested for such roles are the soluble low affinity receptor for IgE (sCD23) and the soluble interleukin-2 receptor (sCD25). To assess serum levels of these factors blood samples were collected at birth and at age 6 in a large nonselected population from Tucson, AZ. Log mean sCD23 and sCD25 levels decreased from birth to age 6, (for sCD23 0.60 ffi 0.26pg/l, n = 340 and 0.53 + 0.28pg/l, n = 333 and for sCD25 1.95 i 0.14pM, n = 304 and 1.86 ffi 0.20pM, n = 327, for the two ages respectively. Anglo children had lower sCD23 levels at birth compared to Hispanic children (p < 0.01); no effect of gender was observed. Skin test reactivity at age 6 was directly related to sCD25 levels at age 6 (p = 0.007) and even levels at birth showed a similar trend (p = 0.06). These relations were distinct from any relation to total serum IgE. No relation was observed with sCD23 levels for either skin test reactivity or serum IgE. The prevalences of asthma, rhinitis and eczema by age 6 were unrelated to sCD25 or sCD23 levels. The results indicate that soluble CD23 and CD25 have higher levels at birth than later in childhood and that the development of skin test reactivity may be associated with regulatory mechanisms involving sCD25, whereas sCD23 was not similarly implicated.

Recurrent cough in childhood and its relation to asthma

Risk factors for recurrent cough (RC) in childhood, and its relation to asthma were investigated as part of the prospective, longitudinal Tucson Children's Respiratory Study. RC, defined as > or = 2 episodes of cough without a cold in the past year, was assessed by questionnaire in 987 children at age 6. Children having RC without wheeze (n = 154) did not differ from children with neither symptom (n = 610) in serum IgE levels, skin test response, size-corrected forced expiratory flow, or percentage of decline following cold air challenge. In contrast, children with both RC and wheeze (n = 116) had significantly more respiratory illness, more atopy, lower flow at end-tidal expiration (V'maxFRC), and greater declines in lung function following cold air challenge than children with neither symptom. Current parental smoking was a risk for RC without wheeze, whereas male gender, maternal allergy, wheezing lower respiratory tract illness (LRI) in early life, and high IgE were significant risks for RC with wheeze, compared with children having neither symptom. RC early in life resolved in the majority of children, between ages 2-3 yr and age 6, and between age 6 and age 11. High IgE and positive skin prick test were associated with persistence of RC to age 6 among children who wheezed, and markers of allergy were associated with persistence of RC between 6 and 11 yr. These findings suggest that recurrent cough in the absence of wheeze differs in important respects from classic asthma, and using the same label to refer to these distinct syndromes may obscure their diverse pathophysiologies.