Inhaled corticosteroid use is associated with increased circulating T regulatory cells in children with asthma.

BACKGROUND: T regulatory (Treg) cells are important in balancing immune responses and dysregulation of Treg cells has been implicated in the pathogenesis of multiple disease states including asthma. In this study, our primary aim was to determine Treg cell frequency in the peripheral blood of children with and without asthma. The secondary aim was to explore the association between Treg cell frequency with allergen sensitization, disease severity and medication use. METHODS: Peripheral blood mononuclear cells from healthy control subjects (N = 93) and asthmatic children of varying disease severity (N = 66) were characterized by multi-parameter flow cytometry. RESULTS: Our findings demonstrate that children with asthma had a significantly increased frequency of Treg cells compared to children without asthma. Using a multivariate model, increased Treg cell frequency in children with asthma was most directly associated with inhaled corticosteroid use, and not asthma severity, allergic sensitization, or atopic status of the asthma. CONCLUSION: We conclude that low dose, local airway administration of corticosteroids is sufficient to impact the frequency of Treg cells in the peripheral blood. These data highlight the importance of considering medication exposure when studying Treg cells and suggest inhaled corticosteroid use in asthmatics may improve disease control through increased Treg cell frequency.

Increased H1N1 infection rate in children with asthma.

RATIONALE: The 2009 H1N1 flu appeared to cause more severe cold symptoms during the 2009-2010 flu season. OBJECTIVES: We evaluated H1N1 infections during peak viral season in children with and without asthma to determine whether the H1N1 infectivity rate and illness severity were greater in subjects with asthma. METHODS: One hundred and eighty children, 4-12 years of age, provided eight consecutive weekly nasal mucus samples from September 5 through October 24, 2009, and scored cold and asthma symptoms daily. Viral diagnostics were performed for all nasal samples. MEASUREMENTS AND MAIN RESULTS: One hundred and sixty-one children (95 with asthma, 66 without asthma) completed at least 6 of the 8 nasal samples. The incidence of H1N1 infection was significantly higher in children with asthma (41%) than in children without asthma (24%; odds ratio, 4; 95% confidence interval, 1.8-9; P < 0.001), but rates of human rhinovirus infection (90% each) and other viral infections (47 vs. 41%) were similar. In children with asthma, there was a nonsignificant trend for increased loss of asthma control during H1N1 infections compared with human rhinovirus infections (38 vs. 21%; odds ratio, 2.6; 95% confidence interval, 0.9-7.2; P = 0.07). CONCLUSIONS: During peak 2009 H1N1 flu season, children with asthma were infected almost twice as often with H1N1 compared with other respiratory viruses. H1N1 infection also caused increased severity of cold symptoms compared with other viral infections. Given the increased susceptibility of children with asthma to infection, these findings reinforce the need for yearly influenza vaccination to prevent infection, and raise new questions about the mechanism for enhanced susceptibility to influenza infection in asthma.

Decreased lung function after preschool wheezing rhinovirus illnesses in children at risk to develop asthma.

BACKGROUND: Preschool rhinovirus (RV) wheezing illnesses predict an increased risk of childhood asthma; however, it is not clear how specific viral illnesses in early life relate to lung function later on in childhood. OBJECTIVE: To determine the relationship of virus-specific wheezing illnesses and lung function in a longitudinal cohort of children at risk for asthma. METHODS: Two hundred thirty-eight children were followed prospectively from birth to 8 years of age. Early life viral wheezing respiratory illnesses were assessed by using standard techniques, and lung function was assessed annually by using spirometry and impulse oscillometry. The relationships of these virus-specific wheezing illnesses and lung function were assessed by using mixed-effect linear regression. RESULTS: Children with RV wheezing illness demonstrated significantly decreased spirometry values, FEV(1) (P = .001), FEV(0.5) (P < .001), FEF(25-75) (P < .001), and also had abnormal impulse oscillometry measures--more negative reactance at 5 Hz (P < .001)--compared with those who did not wheeze with RV. Children who wheezed with respiratory syncytial virus or other viral illnesses did not have any significant differences in spirometric or impulse oscillometry indices when compared with children who did not. Children diagnosed with asthma at ages 6 or 8 years had significantly decreased FEF(25-75) (P = .05) compared with children without asthma. CONCLUSION: Among outpatient viral wheezing illnesses in early childhood, those caused by RV infections are the most significant predictors of decreased lung function up to age 8 years in a high-risk birth cohort. Whether low lung function is a cause and/or effect of RV wheezing illnesses is yet to be determined.

Early childhood weight status in relation to asthma development in high-risk children.

BACKGROUND: Obesity has been proposed to be a risk factor for the development of childhood asthma. OBJECTIVE: We sought to examine weight status from birth to age 5 years in relation to the occurrence of asthma at ages 6 and 8 years. METHODS: Two hundred eighty-five full-term high-risk newborns with at least 1 asthmatic/atopic parent enrolled in the Childhood Origin of Asthma project were studied from birth to age 8 years. Overweight was defined by weight-for-length percentiles of greater than the 85th percentile before the age of 2 years and a body mass index percentile of greater than the 85th percentile at ages 2 to 5 years. RESULTS: No significant concurrent association was found between overweight status and wheezing/asthma occurrence at each year of age. In contrast, longitudinal analyses revealed complex relationships between being overweight and asthma. Being overweight at age 1 year was associated with a decreased risk of asthma at age 6 (odds ratio [OR], 0.32; P = .02) and 8 (OR, 0.35; P = .04) years, as well as better lung function. However, being overweight beyond infancy was not associated with asthma occurrence. In fact, only children who were overweight at age 5 years but not at age 1 year had an increased risk of asthma at age 6 years (OR, 5.78; P = .05). CONCLUSION: In children genetically at high risk of asthma, being overweight at age 1 year was associated with a decreased risk of asthma and better lung function at ages 6 and 8 years. However, being overweight beyond infancy did not have any protective effect and even could confer a higher risk for asthma.

The relationships among immunoglobulin levels, allergic sensitization, and viral respiratory illnesses in early childhood.

IgE plays an essential role in type I allergy, however, there is less information about the relationship between other immunoglobulins (IgA and IgG) and atopic phenotypes in early childhood. We hypothesized that levels of circulating IgA in early childhood would be inversely related to the number of respiratory infections and the risk of becoming sensitized to allergens. Immunoglobulin levels were analyzed (ELISA) in plasma samples (IgG, IgA), and in nasal secretions (IgA) from children participating in a high-risk birth cohort study. Samples were available from 264 children at age 2 yr and 257 children at age 4 yr, and results were compared to rates of respiratory illnesses, allergic sensitization, atopic dermatitis (AD), and asthma. Children who were sensitized to allergens had higher rather than lower levels of circulating IgA. A subgroup analysis showed that IgA levels were increased in relationship to foods sensitization (58 vs. 50 mg/dl, p = 0.003) but not aeroallergen sensitization (52 vs. 53 mg/dl, p = 0.11). IgA levels in the plasma correlated with levels of IgE levels (r(s) =0.19, p = 0.003). Levels of IgE, but not IgG or IgA, were positively correlated with rates of respiratory illnesses, AD, and the risk of developing asthma. Finally, there were no significant relationships between IgA in nasal secretions and infectious outcomes. In conclusion, low-normal concentrations of plasma IgA are associated with a reduced prevalence of allergic sensitization in infancy. Further, levels of IgA and IgG in plasma within the range of normal, and IgA in nasal secretions, do not appear to influence the risk of subsequent respiratory illnesses. Further studies to define relationships between IgA and allergic sensitization are likely to provide new insights into the pathogenesis of allergic diseases in infancy.

Fractional exhaled nitric oxide measurements are most closely associated with allergic sensitization in school-age children.

BACKGROUND: Factors affecting fractional exhaled nitric oxide (FeNO) in early childhood are incompletely understood. OBJECTIVE: To examine the relationships between FeNO and allergic sensitization, total IgE, atopic dermatitis, rhinitis, asthma, and lung function (spirometry) in children. METHODS: Children at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively. FeNO was measured by an online technique at ages 6 and 8 years. Relationships among FeNO, various atopic characteristics, and asthma were evaluated. RESULTS: Reproducible FeNO measurements were obtained in 64% (135/210) of 6-year-old and 93% (180/194) of 8-year-old children. There was seasonal variability in FeNO. Children with aeroallergen sensitization at ages 6 and 8 years had increased levels of FeNO compared with those not sensitized (geometric mean; 6 years, 10.9 vs 6.7 parts per billion [ppb], P < .0001; 8 years, 14.6 vs 7.1 ppb, P < .0001). FeNO was higher in children with asthma than in those without asthma at 8 years but not 6 years of age (6 years, 9.2 vs 8.3 ppb, P = .48; 8 years, 11.5 vs 9.2 ppb, P = .03). At 8 years of age, this difference was no longer significant in a multivariate model that included aeroallergen sensitization (P = .33). There were no correlations between FeNO and spirometric indices at 6 or 8 years of age. CONCLUSION: These findings underscore the importance of evaluating allergen sensitization status when FeNO is used as a potential biomarker in the diagnosis and/or monitoring of atopic diseases, particularly asthma.

Distribution and seasonality of rhinovirus and other respiratory viruses in a cross-section of asthmatic children in Trinidad, West Indies.

BACKGROUND: Childhood asthma in the Caribbean is advancing in prevalence and morbidity. Though viral respiratory tract infections are reported triggers for exacerbations, information on these infections with asthma is sparse in Caribbean territories. We examined the distribution of respiratory viruses and their association with seasons in acute and stable asthmatic children in Trinidad. METHODS: In a cross-sectional study of 70 wheezing children attending the emergency department for nebulisation and 80 stable control subjects (2 to 16 yr of age) in the asthma clinic, nasal specimens were collected during the dry (n = 38, January to May) and rainy (n = 112, June to December) seasons. A multitarget, sensitive, specific high-throughput Respiratory MultiCode assay tested for respiratory-virus sequences for eight distinct groups: human rhinovirus, respiratory syncytial virus, parainfluenza virus, influenza virus, metapneumovirus, adenovirus, coronavirus, and enterovirus. RESULTS: Wheezing children had a higher [chi(2 )= 5.561, p = 0.018] prevalence of respiratory viruses compared with stabilized asthmatics (34.3% (24) versus (vs.) 17.5% (14)). Acute asthmatics were thrice as likely to be infected with a respiratory virus (OR = 2.5, 95% CI = 1.2 - 5.3). The predominant pathogens detected in acute versus stable asthmatics were the rhinovirus (RV) (n = 18, 25.7% vs. n = 7, 8.8%; p = 0.005), respiratory syncytial virus B (RSV B) (n = 2, 2.9% vs. n = 4, 5.0%), and enterovirus (n = 1, 1.4% vs. n = 2, 2.5%). Strong odds for rhinoviral infection were observed among nebulised children compared with stable asthmatics (p = 0.005, OR = 3.6, 95% CI = 1.4 - 9.3,). RV was prevalent throughout the year (Dry, n = 6, 15.8%; Rainy, n = 19, 17.0%) and without seasonal association [chi(2 )= 0.028, p = 0.867]. However it was the most frequently detected virus [Dry = 6/10, (60.0%); Rainy = 19/28, (67.9%)] in both seasons. CONCLUSION: Emergent wheezing illnesses during childhood can be linked to infection with rhinovirus in Trinidad's tropical environment. Viral-induced exacerbations of asthma are independent of seasons in this tropical climate. Further clinical and virology investigations are recommended on the role of infections with the rhinovirus in Caribbean childhood wheeze.

Distribution and seasonality of rhinovirus and other respiratory viruses in a cross-section of asthmatic children in Trinidad, WestIndies

BACKGROUND: Childhood asthma in the Caribbean is advancing in prevalence and morbidity. Though viral respiratory tract infections are reported triggers for exacerbations, information on these infections with asthma is sparse in Caribbean territories. We examined the distribution of respiratory viruses and their association with seasons in acute and stable asthmatic children in Trinidad. METHODS: In a cross-sectional study of 70 wheezing children attending the emergency department for nebulisation and 80 stable control subjects (2 to 16 yr of age) in the asthma clinic, nasal specimens were collected during the dry (n = 38, January to May) and rainy (n = 112, June to December) seasons. Amultitarget, sensitive, specific high-throughput Respiratory MultiCode assay tested for respiratory-virus sequences for eight distinct groups: human rhinovirus, respiratory syncytial virus, parainfluenza virus,influenza virus, metapneumovirus, adenovirus, coronavirus, and enterovirus. RESULTS: Wheezing children had a higher [c2 = 5.561, p = 0.018] prevalence of respiratory viruses compared with stabilized asthmatics (34.3% (24) versus (vs.) 17.5% (14)).... CONCLUSION: Emergent wheezing illnesses during childhood can be linked to infection with rhinovirus in Trinidad's tropical environment. Viral-induced exacerbations of asthma are independent of seasons in this tropical climate. Further clinical and virology investigations are recommended on the role of infections with the rhinovirus in Caribbean childhood wheeze.

Distribution and seasonality of rhinovirus and other respiratory viruses in a cross-section of asthmatic children in Trinidad, West Indies.

BACKGROUND: Childhood asthma in the Caribbean is advancing in prevalence and morbidity. Though viral respiratory tract infections are reported triggers for exacerbations, information on these infections with asthma is sparse in Caribbean territories. We examined the distribution of respiratory viruses and their association with seasons in acute and stable asthmatic children in Trinidad. METHODS: In a cross-sectional study of 70 wheezing children attending the emergency department for nebulisation and 80 stable control subjects (2 to 16 yr of age) in the asthma clinic, nasal specimens were collected during the dry (n=38, January to May) and rainy (n=112, June to December) seasons. A multitarget, sensitive, specific high-throughput Respiratory MultiCode assay tested for respiratory-virus sequences for eight distinct groups: human rhinovirus, respiratory syncytial virus, parainfluenza virus, influenza virus, metapneumovirus, adenovirus, coronavirus, and enterovirus. RESULTS: Wheezing children had a higher [chi square =5.561, p=0.018] prevalence of respiratory viruses compared with stabilized asthmatics (34.3 per cent (24) versus (vs.) 17.5 per cent (14)). Acute asthmatics were thrice as likely to be infected with a respiratory virus (OR = 2.5, 95 per cent CI = 1.2 - 5.3). The predominant pathogens detected in acute versus stable asthmatics were the rhinovirus (RV) (n=18, 25.7 per cent vs. n=7, 8.8 per cent; p=0.005), respiratory syncytial virus B (RSV B) (n=2, 2.9 per cent vs. n=4, 5.0 per cent), and enterovirus (n=1, 1.4 per cent vs. n=2, 2.5 per cent). Strong odds for rhinovirus infection were observed among nebulised children compared with stable asthmatics (p=0.005, OR = 3.6, 95 per cent CI = 1.4 - 9.3,). RV was prevalent throughout the year (Dry, n=6, 15.8 per cent; Rainy, n=19, 17.0 per cent) and without seasonal association [chi square =0.028, p=0.867]...

Wheezing rhinovirus illnesses in early life predict asthma development in high-risk children.

RATIONALE: Virus-induced wheezing episodes in infancy often precede the development of asthma. Whether infections with specific viral pathogens confer differential future asthma risk is incompletely understood. OBJECTIVES: To define the relationship between specific viral illnesses and early childhood asthma development. METHODS: A total of 259 children were followed prospectively from birth to 6 years of age. The etiology and timing of specific viral wheezing respiratory illnesses during early childhood were assessed using nasal lavage, culture, and multiplex reverse transcriptase-polymerase chain reaction. The relationships of these virus-specific wheezing illnesses and other risk factors to the development of asthma were analyzed. MEASUREMENTS AND MAIN RESULTS: Viral etiologies were identified in 90% of wheezing illnesses. From birth to age 3 years, wheezing with respiratory syncytial virus (RSV) (odds ratio [OR], 2.6), rhinovirus (RV) (OR, 9.8), or both RV and RSV (OR , 10) was associated with increased asthma risk at age 6 years. In Year 1, both RV wheezing (OR, 2.8) and aeroallergen sensitization (OR, 3.6) independently increased asthma risk at age 6 years. By age 3 years, wheezing with RV (OR, 25.6) was more strongly associated with asthma at age 6 years than aeroallergen sensitization (OR, 3.4). Nearly 90% (26 of 30) of children who wheezed with RV in Year 3 had asthma at 6 years of age. CONCLUSIONS: Among outpatient viral wheezing illnesses in infancy and early childhood, those caused by RV infections are the most significant predictors of the subsequent development of asthma at age 6 years in a high-risk birth cohort.

Bidirectional interactions between viral respiratory illnesses and cytokine responses in the first year of life.

BACKGROUND: Viral infections are the major cause of acute wheezing illnesses in childhood. Variations in immunologic responses at birth may be determinants of the risk of acquiring these illnesses. OBJECTIVES: To determine the immunologic risk factors for virus-induced wheezing in high-risk infants. METHODS: The study involves 285 children with a parental history of asthma and/or respiratory allergies. Mononuclear cells obtained at birth (umbilical cord blood) and at 1 year of age were incubated with phytohemagglutinin, respiratory syncytial virus, or rhinovirus, and supernatants were analyzed for IL-5, IL-10, IL-13, and IFN-gamma. Nasal secretions obtained at well child visits and during respiratory illnesses were analyzed for common respiratory viruses. RESULTS: Respiratory syncytial virus-induced wheezing was associated with reduced phytohemagglutinin-induced IL-13 responses (medians, 213 vs 304 pg/mL; P = .026) from cord blood cells, and similar trends were found for wheezing in general. Furthermore, median IL-13 responses diminished by 28% in non-wheezing children by age 1 year, versus only 3% in wheezing children (P = .013). Children with > or =2 episodes of wheezing had lower phytohemagglutinin-induced IFN-gamma responses and were less likely to have rhinovirus-induced IFN-gamma responses at birth (P < .05). Finally, children with measurable cord blood IFN responses to respiratory syncytial virus were less likely to wheeze in their first year (odds ratio, 0.43 [0.23, 0.79]). CONCLUSION: In children with a family history of allergies and/or asthma, mononuclear cell phytohemagglutinin-induced IL-13 and virus-induced IFN-gamma responses at birth are indicative of the risk for wheezing in the first year of life.

Viral infections, cytokine dysregulation and the origins of childhood asthma and allergic diseases.

BACKGROUND: The origins of asthma and allergic disease begin in early life for many individuals. It is vital to understand the factors and/or events leading to their development. METHODS: The Childhood Origins of Asthma project evaluated children at high risk for asthma to study the relationships among viral infections, environmental factors, immune dysregulation, genetic factors, and the development of atopic diseases. Consequently wheezing illnesses, viral respiratory pathogen identification, and in vitro cytokine response profiles were comprehensively evaluated from birth to 3 years of age, and associations of the observed phenotypes with genetic polymorphisms were investigated. RESULTS: For the entire cohort, cytokine responses did not develop according to a strict T helper cell 1 or T helper cell 2 polarization pattern during infancy. Increased cord blood mononuclear cell phytohemagglutin-induced interferon-gamma responses of mononuclear cells were associated with decreased numbers of moderate to severe viral infections during infancy, especially among subjects with the greatest exposure to other children. In support of the hygiene hypothesis, an increased frequency of viral infections in infancy resulted in increased mitogen-induced interferon-gamma responses at 1 year of age. First year wheezing illnesses caused by respiratory viral infection were the strongest predictor of subsequent third year wheezing. Also, genotypic variation interacting with environmental factors, including day care, was associated with clinical and immunologic phenotypes that may precede the development of asthma. CONCLUSIONS: Associations between clinical wheezing, viral identification, specific cytokine responses and genetic variation provide insight into the immunopathogenesis of childhood asthma and allergic diseases.

Rhinovirus illnesses during infancy predict subsequent childhood wheezing.

BACKGROUND: The contribution of viral respiratory infections during infancy to the development of subsequent wheezing and/or allergic diseases in early childhood is not established. OBJECTIVE: To evaluate these relationships prospectively from birth to 3 years of age in 285 children genetically at high risk for developing allergic respiratory diseases. METHODS: By using nasal lavage, the relationship of timing, severity, and etiology of viral respiratory infections during infancy to wheezing in the 3rd year of life was evaluated. In addition, genetic and environmental factors that could modify risk of infections and wheezing prevalence were analyzed. RESULTS: Risk factors for 3rd year wheezing were passive smoke exposure (odds ratio [OR]=2.1), older siblings (OR=2.5), allergic sensitization to foods at age 1 year (OR=2.0), any moderate to severe respiratory illness without wheezing during infancy (OR=3.6), and at least 1 wheezing illness with respiratory syncytial virus (RSV; OR=3.0), rhinovirus (OR=10) and/or non-rhinovirus/RSV pathogens (OR=3.9) during infancy. When viral etiology was considered, 1st-year wheezing illnesses caused by rhinovirus infection were the strongest predictor of subsequent 3rd year wheezing (OR=6.6; P < .0001). Moreover, 63% of infants who wheezed during rhinovirus seasons continued to wheeze in the 3rd year of life, compared with only 20% of all other infants (OR=6.6; P < .0001). CONCLUSION: In this population of children at increased risk of developing allergies and asthma, the most significant risk factor for the development of preschool childhood wheezing is the occurrence of symptomatic rhinovirus illnesses during infancy that are clinically and prognostically informative based on their seasonal nature.

Cytokine response patterns, exposure to viruses, and respiratory infections in the first year of life.

Daycare attendance and siblings are associated with viral-induced wheezing in children. Preexisting immunologic factors may influence the expression of viral infections in infancy, and in turn, recurrent infections may influence the development of immune responses. A total of 285 children were enrolled in the Childhood Origins of Asthma Project at birth and followed for at least 1 year. Cord blood and 1-year mononuclear cells were stimulated with phytohemagglutinin, and cytokine-response profiles were measured by enzyme-linked immunosorbent assay. Nasal lavage was performed for moderate to severe respiratory illnesses. Daycare attendance and/or siblings significantly increased the likelihood of contracting respiratory syncytial virus (1.5-1.6-fold increase) and rhinovirus (1.8-2.1-fold increase), and increased the risk of rhinovirus-induced wheezing (14-18% vs. 2%, p = 0.011). Cord blood IFN-gamma responses were inversely related to the frequency of viral respiratory infections (r(s) = -0.11, p = 0.05), and more significant for subjects with high exposure to other children (r(s) = -0.27, p = 0.028). The interval change in infantile IFN-gamma responses correlated positively with the frequency of viral infections in infancy (r(s) = 0.12, p = 0.047). These data suggest that neonatal IFN-gamma responses may influence antiviral activity, or may represent a marker of antiviral immunity maturation. Conversely, the frequency of viral infections in infancy can influence IFN-gamma responses.

Effects of dog ownership and genotype on immune development and atopy in infancy.

BACKGROUND: Exposure to furred pets might confer protection against the development of allergic sensitization through a mechanism that is incompletely understood. OBJECTIVE: The objective of this study was to determine the effects of pet exposure and genotype on immunologic development and the incidence of atopic markers and diseases in the first year of life. METHODS: Pet exposure in the home was compared with cytokine secretion patterns (mitogen-stimulated mononuclear cells at birth and age 1 year) and indicators of atopy (allergen-specific and total IgE, eosinophilia, food allergy, atopic dermatitis) in 285 infants. Interactions with genotype at the CD14 locus were also evaluated in the data analyses. RESULTS: Exposure to dogs was associated with reduced allergen sensitization (19% vs 33%, P =.020) and atopic dermatitis (30% vs 51%, P <.001). The risk for atopic dermatitis was further influenced by genotype at the CD14 locus (P =.006), even after adjusting for exposure to dogs (P =.003). Furthermore, infants with the genotype -159TT were less likely to develop atopic dermatitis if they were exposed to a dog (5% vs 43%, P =.04). Last, dog exposure was associated with increased IL-10 (117 vs 79 pg/mL, P =.002) and IL-13 (280 vs 226 pg/mL, P =.013) responses at age 1 year. CONCLUSIONS: Having a dog in infancy is associated with higher IL-10 and IL-13 cytokine secretion profiles and reduced allergic sensitization and atopic dermatitis. These findings suggest that postnatal exposure to dogs can influence immune development in a genotype-specific fashion and thereby attenuate the development of atopy in at-risk children.

Developmental cytokine response profiles and the clinical and immunologic expression of atopy during the first year of life.

BACKGROUND: Allergic diseases have been linked to abnormal patterns of immune development, and this has stimulated efforts to define the precise patterns of cytokine dysregulation that are associated with specific atopic phenotypes. OBJECTIVE: Cytokine-response profiles were prospectively analyzed over the first year of life and compared with the clinical and immunologic expressions of atopy. METHODS: Umbilical cord and 1-year PBMCs were obtained from 285 subjects from allergic families. PHA-stimulated cytokine-response profiles (IL-5, IL-10, IL-13, and IFN-gamma) were compared with blood eosinophil counts and total and specific IgE levels (dust mites, cat, egg, Alternaria species, peanut, milk, and dog) at age 1 year and at the development of atopic dermatitis and food allergy. RESULTS: For the cohort as a whole, cytokine responses did not evolve according to a strict TH1 or TH2 polarization pattern. PHA-stimulated cord blood cells secreted low levels of IL-5 (2.1 pg/mL), moderate levels of IFN-gamma (57.4 pg/mL), and greater amounts of IL-13 (281.8 pg/mL). From birth to 1 year, IL-5 responses dramatically increased, whereas IL-13 and IFN-gamma responses significantly decreased. Reduced cord blood secretion of IL-10 and IFN-gamma was associated with subsequent sensitization to egg. In addition, there was evidence of TH2 polarization (increased IL-5 and IL-13 levels) associated with blood eosinophilia and increased total IgE levels by age 1 year. CONCLUSION: These findings demonstrate that cytokine responses change markedly during the first year of life and provide further evidence of a close relationship between TH2 skewing of immune responses and the incidence of atopic manifestations in children.

Relationships among specific viral pathogens, virus-induced interleukin-8, and respiratory symptoms in infancy.

Both virus-mediated damage to airway tissues and induction of pro-inflammatory cytokines such as interleukin-8 (IL-8) could contribute to symptom severity during viral respiratory infections in children. To test the hypothesis that IL-8 contributes to the pathogenesis of respiratory symptoms during naturally acquired respiratory viral infections in children, nasal wash samples collected from infants with acute viral infections (n = 198) or from healthy uninfected infants (n = 31) were analysed for IL-8. Nasal wash IL-8 was positively related to age in uninfected children (rs = 0.36, p < 0.05). Respiratory syncytial virus (RSV) infection caused more severe respiratory symptoms compared to infections with influenza A, parainfluenza viruses, or rhinoviruses. In addition, RSV, parainfluenza and rhinovirus infections increased levels of IL-8 in nasal lavage fluid, and there were some differences in the ability of the viruses to induce IL-8 production (RSV>influenza, p < 0.05). Finally, there were significant correlations between nasal wash IL-8 levels and symptom scores during infections with rhinovirus (rs = 0.56, p < 0.001) or influenza A (rs = 0.45, p < 0.05), but not with parainfluenza virus or RSV. These findings provide evidence of a close relationship between the generation of IL-8 and symptoms during acute community-acquired infections with rhinovirus or influenza A. In contrast, for RSV and parainfluenza infections, factors in addition to IL-8 production appear to contribute to the generation of clinical symptoms.